content/browser/accessibility/browser_accessibility_manager_mac.mm - chromium/src - Git at Google

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "content/browser/accessibility/browser_accessibility_manager_mac.h"

 #import "base/mac/mac_util.h"
 #import "base/mac/sdk_forward_declarations.h"
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
 #import "content/browser/accessibility/browser_accessibility_mac.h"
 #include "content/common/accessibility_messages.h"

 namespace {

 // Declare undocumented accessibility constants and enums only present in
 // WebKit.

 enum AXTextStateChangeType {
   AXTextStateChangeTypeUnknown,
   AXTextStateChangeTypeEdit,
   AXTextStateChangeTypeSelectionMove,
   AXTextStateChangeTypeSelectionExtend
 };

 enum AXTextSelectionDirection {
   AXTextSelectionDirectionUnknown,
   AXTextSelectionDirectionBeginning,
   AXTextSelectionDirectionEnd,
   AXTextSelectionDirectionPrevious,
   AXTextSelectionDirectionNext,
   AXTextSelectionDirectionDiscontiguous
 };

 enum AXTextSelectionGranularity {
   AXTextSelectionGranularityUnknown,
   AXTextSelectionGranularityCharacter,
   AXTextSelectionGranularityWord,
   AXTextSelectionGranularityLine,
   AXTextSelectionGranularitySentence,
   AXTextSelectionGranularityParagraph,
   AXTextSelectionGranularityPage,
   AXTextSelectionGranularityDocument,
   AXTextSelectionGranularityAll
 };

 enum AXTextEditType {
   AXTextEditTypeUnknown,
   AXTextEditTypeDelete,
   AXTextEditTypeInsert,
   AXTextEditTypeTyping,
   AXTextEditTypeDictation,
   AXTextEditTypeCut,
   AXTextEditTypePaste,
   AXTextEditTypeAttributesChange
 };

 NSString* const NSAccessibilityAutocorrectionOccurredNotification =
     @"AXAutocorrectionOccurred";
 NSString* const NSAccessibilityLayoutCompleteNotification =
     @"AXLayoutComplete";
 NSString* const NSAccessibilityLoadCompleteNotification =
     @"AXLoadComplete";
 NSString* const NSAccessibilityInvalidStatusChangedNotification =
     @"AXInvalidStatusChanged";
 NSString* const NSAccessibilityLiveRegionChangedNotification =
     @"AXLiveRegionChanged";
 NSString* const NSAccessibilityExpandedChanged =
     @"AXExpandedChanged";
 NSString* const NSAccessibilityMenuItemSelectedNotification =
     @"AXMenuItemSelected";

 // Attributes used for NSAccessibilitySelectedTextChangedNotification and
 // NSAccessibilityValueChangedNotification.
 NSString* const NSAccessibilityTextStateChangeTypeKey =
     @"AXTextStateChangeType";
 NSString* const NSAccessibilityTextStateSyncKey = @"AXTextStateSync";
 NSString* const NSAccessibilityTextSelectionDirection =
     @"AXTextSelectionDirection";
 NSString* const NSAccessibilityTextSelectionGranularity =
     @"AXTextSelectionGranularity";
 NSString* const NSAccessibilityTextSelectionChangedFocus =
     @"AXTextSelectionChangedFocus";
 NSString* const NSAccessibilitySelectedTextMarkerRangeAttribute =
     @"AXSelectedTextMarkerRange";
 NSString* const NSAccessibilityTextChangeElement = @"AXTextChangeElement";
 NSString* const NSAccessibilityTextEditType = @"AXTextEditType";
 NSString* const NSAccessibilityTextChangeValue = @"AXTextChangeValue";
 NSString* const NSAccessibilityTextChangeValueLength =
     @"AXTextChangeValueLength";
 NSString* const NSAccessibilityTextChangeValues = @"AXTextChangeValues";

 }  // namespace

 namespace content {

 // static
 BrowserAccessibilityManager* BrowserAccessibilityManager::Create(
     const ui::AXTreeUpdate& initial_tree,
     BrowserAccessibilityDelegate* delegate,
     BrowserAccessibilityFactory* factory) {
   return new BrowserAccessibilityManagerMac(
       NULL, initial_tree, delegate, factory);
 }

 BrowserAccessibilityManagerMac::BrowserAccessibilityManagerMac(
     NSView* parent_view,
     const ui::AXTreeUpdate& initial_tree,
     BrowserAccessibilityDelegate* delegate,
     BrowserAccessibilityFactory* factory)
     : BrowserAccessibilityManager(delegate, factory),
       parent_view_(parent_view) {
   Initialize(initial_tree);
 }

 BrowserAccessibilityManagerMac::~BrowserAccessibilityManagerMac() {}

 // static
 ui::AXTreeUpdate
     BrowserAccessibilityManagerMac::GetEmptyDocument() {
   ui::AXNodeData empty_document;
   empty_document.id = 0;
   empty_document.role = ui::AX_ROLE_ROOT_WEB_AREA;
   empty_document.state =
       1 << ui::AX_STATE_READ_ONLY;
   ui::AXTreeUpdate update;
   update.root_id = empty_document.id;
   update.nodes.push_back(empty_document);
   return update;
 }

 BrowserAccessibility* BrowserAccessibilityManagerMac::GetFocus() {
   BrowserAccessibility* focus = BrowserAccessibilityManager::GetFocus();

   // On Mac, list boxes should always get focus on the whole list, otherwise
   // information about the number of selected items will never be reported.
   // For editable combo boxes, focus should stay on the combo box so the user
   // will not be taken out of the combo box while typing.
   if (focus && (focus->GetRole() == ui::AX_ROLE_LIST_BOX ||
                 (focus->GetRole() == ui::AX_ROLE_COMBO_BOX &&
                  focus->HasState(ui::AX_STATE_EDITABLE)))) {
     return focus;
   }

   // For other roles, follow the active descendant.
   return GetActiveDescendant(focus);
 }

 void BrowserAccessibilityManagerMac::NotifyAccessibilityEvent(
     BrowserAccessibilityEvent::Source source,
     ui::AXEvent event_type,
     BrowserAccessibility* node) {
   if (!node->IsNative())
     return;

   auto native_node = ToBrowserAccessibilityCocoa(node);
   DCHECK(native_node);

   // Refer to |AXObjectCache::postPlatformNotification| in WebKit source code.
   NSString* mac_notification;
   switch (event_type) {
     case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED:
       if (node->GetRole() == ui::AX_ROLE_TREE) {
         mac_notification = NSAccessibilitySelectedRowsChangedNotification;
       } else if (node->GetRole() == ui::AX_ROLE_COMBO_BOX) {
         // Even though the selected item in the combo box has changed, we don't
         // want to post a focus change because this will take the focus out of
         // the combo box where the user might be typing.
         mac_notification = NSAccessibilitySelectedChildrenChangedNotification;
       } else {
         // In all other cases we should post
         // |NSAccessibilityFocusedUIElementChangedNotification|, but this is
         // handled elsewhere.
         return;
       }
       break;
     case ui::AX_EVENT_AUTOCORRECTION_OCCURED:
       mac_notification = NSAccessibilityAutocorrectionOccurredNotification;
       break;
     case ui::AX_EVENT_FOCUS:
       mac_notification = NSAccessibilityFocusedUIElementChangedNotification;
       break;
     case ui::AX_EVENT_LAYOUT_COMPLETE:
       mac_notification = NSAccessibilityLayoutCompleteNotification;
       break;
     case ui::AX_EVENT_LOAD_COMPLETE:
       mac_notification = NSAccessibilityLoadCompleteNotification;
       break;
     case ui::AX_EVENT_INVALID_STATUS_CHANGED:
       mac_notification = NSAccessibilityInvalidStatusChangedNotification;
       break;
     case ui::AX_EVENT_SELECTED_CHILDREN_CHANGED:
       if (node->GetRole() == ui::AX_ROLE_GRID ||
           node->GetRole() == ui::AX_ROLE_TABLE) {
         mac_notification = NSAccessibilitySelectedRowsChangedNotification;
       } else {
         mac_notification = NSAccessibilitySelectedChildrenChangedNotification;
       }
       break;
     case ui::AX_EVENT_DOCUMENT_SELECTION_CHANGED: {
       mac_notification = NSAccessibilitySelectedTextChangedNotification;
       // WebKit fires a notification both on the focused object and the root.
       BrowserAccessibility* focus = GetFocus();
       if (!focus)
         break;  // Just fire a notification on the root.
       NSAccessibilityPostNotification(ToBrowserAccessibilityCocoa(focus),
                                       mac_notification);

       if (base::mac::IsOSElCapitanOrLater()) {
         // |NSAccessibilityPostNotificationWithUserInfo| should be used on OS X
         // 10.11 or later to notify Voiceover about text selection changes. This
         // API has been present on versions of OS X since 10.7 but doesn't
         // appear to be needed by Voiceover before version 10.11.
         NSDictionary* user_info =
             GetUserInfoForSelectedTextChangedNotification();

         BrowserAccessibility* root = GetRoot();
         if (!root)
           return;

         NSAccessibilityPostNotificationWithUserInfo(
             ToBrowserAccessibilityCocoa(focus), mac_notification, user_info);
         NSAccessibilityPostNotificationWithUserInfo(
             ToBrowserAccessibilityCocoa(root), mac_notification, user_info);
         return;
       }
       break;
     }
     case ui::AX_EVENT_CHECKED_STATE_CHANGED:
       mac_notification = NSAccessibilityValueChangedNotification;
       break;
     case ui::AX_EVENT_VALUE_CHANGED:
       mac_notification = NSAccessibilityValueChangedNotification;
       if (base::mac::IsOSElCapitanOrLater() && text_edits_.size()) {
         // It seems that we don't need to distinguish between deleted and
         // inserted text for now.
         base::string16 deleted_text;
         base::string16 inserted_text;
         int32_t id = node->GetId();
         const auto iterator = text_edits_.find(id);
         if (iterator != text_edits_.end())
           inserted_text = iterator->second;
         NSDictionary* user_info = GetUserInfoForValueChangedNotification(
             native_node, deleted_text, inserted_text);

         BrowserAccessibility* root = GetRoot();
         if (!root)
           return;

         NSAccessibilityPostNotificationWithUserInfo(
             native_node, mac_notification, user_info);
         NSAccessibilityPostNotificationWithUserInfo(
             ToBrowserAccessibilityCocoa(root), mac_notification, user_info);
         return;
       }
       break;
     // TODO(nektar): Need to add an event for live region created.
     case ui::AX_EVENT_LIVE_REGION_CHANGED:
       mac_notification = NSAccessibilityLiveRegionChangedNotification;
       break;
     case ui::AX_EVENT_ROW_COUNT_CHANGED:
       mac_notification = NSAccessibilityRowCountChangedNotification;
       break;
     case ui::AX_EVENT_ROW_EXPANDED:
       mac_notification = NSAccessibilityRowExpandedNotification;
       break;
     case ui::AX_EVENT_ROW_COLLAPSED:
       mac_notification = NSAccessibilityRowCollapsedNotification;
       break;
     // TODO(nektar): Add events for busy.
     case ui::AX_EVENT_EXPANDED_CHANGED:
       mac_notification = NSAccessibilityExpandedChanged;
       break;
     // TODO(nektar): Support menu open/close notifications.
     case ui::AX_EVENT_MENU_LIST_ITEM_SELECTED:
       mac_notification = NSAccessibilityMenuItemSelectedNotification;
       break;

     // These events are not used on Mac for now.
     case ui::AX_EVENT_ALERT:
     case ui::AX_EVENT_TEXT_CHANGED:
     case ui::AX_EVENT_CHILDREN_CHANGED:
     case ui::AX_EVENT_MENU_LIST_VALUE_CHANGED:
     case ui::AX_EVENT_SCROLL_POSITION_CHANGED:
     case ui::AX_EVENT_SCROLLED_TO_ANCHOR:
     case ui::AX_EVENT_ARIA_ATTRIBUTE_CHANGED:
     case ui::AX_EVENT_LOCATION_CHANGED:
       return;

     // Deprecated events.
     case ui::AX_EVENT_BLUR:
     case ui::AX_EVENT_HIDE:
     case ui::AX_EVENT_HOVER:
     case ui::AX_EVENT_TEXT_SELECTION_CHANGED:
     case ui::AX_EVENT_SHOW:
       return;
     default:
       DLOG(WARNING) << "Unknown accessibility event: " << event_type;
       return;
   }

   NSAccessibilityPostNotification(native_node, mac_notification);
 }

 void BrowserAccessibilityManagerMac::OnAccessibilityEvents(
     const std::vector<AXEventNotificationDetails>& details) {
   text_edits_.clear();
   // Call the base method last as it might delete the tree if it receives an
   // invalid message.
   BrowserAccessibilityManager::OnAccessibilityEvents(details);
 }

 void BrowserAccessibilityManagerMac::OnNodeDataWillChange(
     ui::AXTree* tree,
     const ui::AXNodeData& old_node_data,
     const ui::AXNodeData& new_node_data) {
   BrowserAccessibilityManager::OnNodeDataWillChange(tree, old_node_data,
                                                     new_node_data);

   // Starting from OS X 10.11, if the user has edited some text we need to
   // dispatch the actual text that changed on the value changed notification.
   // We run this code on all OS X versions to get the highest test coverage.
   base::string16 old_text, new_text;
   ui::AXRole role = new_node_data.role;
   if (role == ui::AX_ROLE_COMBO_BOX || role == ui::AX_ROLE_SEARCH_BOX ||
       role == ui::AX_ROLE_TEXT_FIELD) {
     old_text = old_node_data.GetString16Attribute(ui::AX_ATTR_VALUE);
     new_text = new_node_data.GetString16Attribute(ui::AX_ATTR_VALUE);
   } else if (new_node_data.state & (1 << ui::AX_STATE_EDITABLE)) {
     old_text = old_node_data.GetString16Attribute(ui::AX_ATTR_NAME);
     new_text = new_node_data.GetString16Attribute(ui::AX_ATTR_NAME);
   }

   if ((old_text.empty() && new_text.empty()) ||
       old_text.length() == new_text.length()) {
     return;
   }

   if (old_text.length() < new_text.length()) {
     // Insertion.
     size_t i = 0;
     while (i < old_text.length() && i < new_text.length() &&
            old_text[i] == new_text[i]) {
       ++i;
     }
     size_t length = (new_text.length() - i) - (old_text.length() - i);
     base::string16 inserted_text = new_text.substr(i, length);
     text_edits_[new_node_data.id] = inserted_text;
   } else {
     // Deletion.
     size_t i = 0;
     while (i < old_text.length() && i < new_text.length() &&
            old_text[i] == new_text[i]) {
       ++i;
     }
     size_t length = (old_text.length() - i) - (new_text.length() - i);
     base::string16 deleted_text = old_text.substr(i, length);
     text_edits_[new_node_data.id] = deleted_text;
   }
 }

 void BrowserAccessibilityManagerMac::OnAtomicUpdateFinished(
     ui::AXTree* tree,
     bool root_changed,
     const std::vector<ui::AXTreeDelegate::Change>& changes) {
   BrowserAccessibilityManager::OnAtomicUpdateFinished(
       tree, root_changed, changes);

   bool created_live_region = false;
   for (size_t i = 0; i < changes.size(); ++i) {
     if (changes[i].type != NODE_CREATED && changes[i].type != SUBTREE_CREATED)
       continue;

     const ui::AXNode* changed_node = changes[i].node;
     DCHECK(changed_node);
     BrowserAccessibility* obj = GetFromAXNode(changed_node);
     if (obj && obj->HasStringAttribute(ui::AX_ATTR_LIVE_STATUS)) {
       created_live_region = true;
       break;
     }
   }

   if (!created_live_region)
     return;

   // This code is to work around a bug in VoiceOver, where a new live
   // region that gets added is ignored. VoiceOver seems to only scan the
   // page for live regions once. By recreating the NSAccessibility
   // object for the root of the tree, we force VoiceOver to clear out its
   // internal state and find newly-added live regions this time.
   BrowserAccessibilityMac* root =
       static_cast<BrowserAccessibilityMac*>(GetRoot());
   if (root) {
     root->RecreateNativeObject();
     NotifyAccessibilityEvent(
         BrowserAccessibilityEvent::FromTreeChange,
         ui::AX_EVENT_CHILDREN_CHANGED,
         root);
   }
 }

 NSDictionary* BrowserAccessibilityManagerMac::
     GetUserInfoForSelectedTextChangedNotification() {
   NSMutableDictionary* user_info = [[[NSMutableDictionary alloc] init]
       autorelease];
   [user_info setObject:@YES forKey:NSAccessibilityTextStateSyncKey];
   [user_info setObject:@(AXTextStateChangeTypeUnknown)
                 forKey:NSAccessibilityTextStateChangeTypeKey];
   [user_info setObject:@(AXTextSelectionDirectionUnknown)
                 forKey:NSAccessibilityTextSelectionDirection];
   [user_info setObject:@(AXTextSelectionGranularityUnknown)
                 forKey:NSAccessibilityTextSelectionGranularity];
   [user_info setObject:@YES forKey:NSAccessibilityTextSelectionChangedFocus];

   int32_t focus_id = GetTreeData().sel_focus_object_id;
   BrowserAccessibility* focus_object = GetFromID(focus_id);
   if (focus_object) {
     focus_object = focus_object->GetClosestPlatformObject();
     auto native_focus_object = ToBrowserAccessibilityCocoa(focus_object);
     if (native_focus_object && [native_focus_object instanceActive]) {
       [user_info setObject:[native_focus_object selectedTextMarkerRange]
                     forKey:NSAccessibilitySelectedTextMarkerRangeAttribute];
       [user_info setObject:native_focus_object
                     forKey:NSAccessibilityTextChangeElement];
     }
   }

   return user_info;
 }

 NSDictionary*
 BrowserAccessibilityManagerMac::GetUserInfoForValueChangedNotification(
     const BrowserAccessibilityCocoa* native_node,
     const base::string16& deleted_text,
     const base::string16& inserted_text) const {
   DCHECK(native_node);
   if (deleted_text.empty() && inserted_text.empty())
     return nil;

   NSMutableArray* changes = [[[NSMutableArray alloc] init] autorelease];
   if (!deleted_text.empty()) {
     [changes addObject:@{
       NSAccessibilityTextEditType : @(AXTextEditTypeUnknown),
       NSAccessibilityTextChangeValueLength : @(deleted_text.length()),
       NSAccessibilityTextChangeValue : base::SysUTF16ToNSString(deleted_text)
     }];
   }
   if (!inserted_text.empty()) {
     [changes addObject:@{
       NSAccessibilityTextEditType : @(AXTextEditTypeUnknown),
       NSAccessibilityTextChangeValueLength : @(inserted_text.length()),
       NSAccessibilityTextChangeValue : base::SysUTF16ToNSString(inserted_text)
     }];
   }

   return @{
     NSAccessibilityTextStateChangeTypeKey : @(AXTextStateChangeTypeEdit),
     NSAccessibilityTextChangeValues : changes,
     NSAccessibilityTextChangeElement : native_node
   };
 }

 }  // namespace content
	// Copyright (c) 2012 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "content/browser/accessibility/browser_accessibility_manager_mac.h"

	#import "base/mac/mac_util.h"
	#import "base/mac/sdk_forward_declarations.h"
	#include "base/logging.h"
	#include "base/strings/sys_string_conversions.h"
	#include "base/strings/utf_string_conversions.h"
	#import "content/browser/accessibility/browser_accessibility_cocoa.h"
	#import "content/browser/accessibility/browser_accessibility_mac.h"
	#include "content/common/accessibility_messages.h"

	namespace {

	// Declare undocumented accessibility constants and enums only present in
	// WebKit.

	enum AXTextStateChangeType {
	AXTextStateChangeTypeUnknown,
	AXTextStateChangeTypeEdit,
	AXTextStateChangeTypeSelectionMove,
	AXTextStateChangeTypeSelectionExtend
	};

	enum AXTextSelectionDirection {
	AXTextSelectionDirectionUnknown,
	AXTextSelectionDirectionBeginning,
	AXTextSelectionDirectionEnd,
	AXTextSelectionDirectionPrevious,
	AXTextSelectionDirectionNext,
	AXTextSelectionDirectionDiscontiguous
	};

	enum AXTextSelectionGranularity {
	AXTextSelectionGranularityUnknown,
	AXTextSelectionGranularityCharacter,
	AXTextSelectionGranularityWord,
	AXTextSelectionGranularityLine,
	AXTextSelectionGranularitySentence,
	AXTextSelectionGranularityParagraph,
	AXTextSelectionGranularityPage,
	AXTextSelectionGranularityDocument,
	AXTextSelectionGranularityAll
	};

	enum AXTextEditType {
	AXTextEditTypeUnknown,
	AXTextEditTypeDelete,
	AXTextEditTypeInsert,
	AXTextEditTypeTyping,
	AXTextEditTypeDictation,
	AXTextEditTypeCut,
	AXTextEditTypePaste,
	AXTextEditTypeAttributesChange
	};

	NSString* const NSAccessibilityAutocorrectionOccurredNotification =
	@"AXAutocorrectionOccurred";
	NSString* const NSAccessibilityLayoutCompleteNotification =
	@"AXLayoutComplete";
	NSString* const NSAccessibilityLoadCompleteNotification =
	@"AXLoadComplete";
	NSString* const NSAccessibilityInvalidStatusChangedNotification =
	@"AXInvalidStatusChanged";
	NSString* const NSAccessibilityLiveRegionChangedNotification =
	@"AXLiveRegionChanged";
	NSString* const NSAccessibilityExpandedChanged =
	@"AXExpandedChanged";
	NSString* const NSAccessibilityMenuItemSelectedNotification =
	@"AXMenuItemSelected";

	// Attributes used for NSAccessibilitySelectedTextChangedNotification and
	// NSAccessibilityValueChangedNotification.
	NSString* const NSAccessibilityTextStateChangeTypeKey =
	@"AXTextStateChangeType";
	NSString* const NSAccessibilityTextStateSyncKey = @"AXTextStateSync";
	NSString* const NSAccessibilityTextSelectionDirection =
	@"AXTextSelectionDirection";
	NSString* const NSAccessibilityTextSelectionGranularity =
	@"AXTextSelectionGranularity";
	NSString* const NSAccessibilityTextSelectionChangedFocus =
	@"AXTextSelectionChangedFocus";
	NSString* const NSAccessibilitySelectedTextMarkerRangeAttribute =
	@"AXSelectedTextMarkerRange";
	NSString* const NSAccessibilityTextChangeElement = @"AXTextChangeElement";
	NSString* const NSAccessibilityTextEditType = @"AXTextEditType";
	NSString* const NSAccessibilityTextChangeValue = @"AXTextChangeValue";
	NSString* const NSAccessibilityTextChangeValueLength =
	@"AXTextChangeValueLength";
	NSString* const NSAccessibilityTextChangeValues = @"AXTextChangeValues";

	} // namespace

	namespace content {

	// static
	BrowserAccessibilityManager* BrowserAccessibilityManager::Create(
	const ui::AXTreeUpdate& initial_tree,
	BrowserAccessibilityDelegate* delegate,
	BrowserAccessibilityFactory* factory) {
	return new BrowserAccessibilityManagerMac(
	NULL, initial_tree, delegate, factory);
	}

	BrowserAccessibilityManagerMac::BrowserAccessibilityManagerMac(
	NSView* parent_view,
	const ui::AXTreeUpdate& initial_tree,
	BrowserAccessibilityDelegate* delegate,
	BrowserAccessibilityFactory* factory)
	: BrowserAccessibilityManager(delegate, factory),
	parent_view_(parent_view) {
	Initialize(initial_tree);
	}

	BrowserAccessibilityManagerMac::~BrowserAccessibilityManagerMac() {}

	// static
	ui::AXTreeUpdate
	BrowserAccessibilityManagerMac::GetEmptyDocument() {
	ui::AXNodeData empty_document;
	empty_document.id = 0;
	empty_document.role = ui::AX_ROLE_ROOT_WEB_AREA;
	empty_document.state =
	1 << ui::AX_STATE_READ_ONLY;
	ui::AXTreeUpdate update;
	update.root_id = empty_document.id;
	update.nodes.push_back(empty_document);
	return update;
	}

	BrowserAccessibility* BrowserAccessibilityManagerMac::GetFocus() {
	BrowserAccessibility* focus = BrowserAccessibilityManager::GetFocus();

	// On Mac, list boxes should always get focus on the whole list, otherwise
	// information about the number of selected items will never be reported.
	// For editable combo boxes, focus should stay on the combo box so the user
	// will not be taken out of the combo box while typing.
	if (focus && (focus->GetRole() == ui::AX_ROLE_LIST_BOX \|\|
	(focus->GetRole() == ui::AX_ROLE_COMBO_BOX &&
	focus->HasState(ui::AX_STATE_EDITABLE)))) {
	return focus;
	}

	// For other roles, follow the active descendant.
	return GetActiveDescendant(focus);
	}

	void BrowserAccessibilityManagerMac::NotifyAccessibilityEvent(
	BrowserAccessibilityEvent::Source source,
	ui::AXEvent event_type,
	BrowserAccessibility* node) {
	if (!node->IsNative())
	return;

	auto native_node = ToBrowserAccessibilityCocoa(node);
	DCHECK(native_node);

	// Refer to \|AXObjectCache::postPlatformNotification\| in WebKit source code.
	NSString* mac_notification;
	switch (event_type) {
	case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED:
	if (node->GetRole() == ui::AX_ROLE_TREE) {
	mac_notification = NSAccessibilitySelectedRowsChangedNotification;
	} else if (node->GetRole() == ui::AX_ROLE_COMBO_BOX) {
	// Even though the selected item in the combo box has changed, we don't
	// want to post a focus change because this will take the focus out of
	// the combo box where the user might be typing.
	mac_notification = NSAccessibilitySelectedChildrenChangedNotification;
	} else {
	// In all other cases we should post
	// \|NSAccessibilityFocusedUIElementChangedNotification\|, but this is
	// handled elsewhere.
	return;
	}
	break;
	case ui::AX_EVENT_AUTOCORRECTION_OCCURED:
	mac_notification = NSAccessibilityAutocorrectionOccurredNotification;
	break;
	case ui::AX_EVENT_FOCUS:
	mac_notification = NSAccessibilityFocusedUIElementChangedNotification;
	break;
	case ui::AX_EVENT_LAYOUT_COMPLETE:
	mac_notification = NSAccessibilityLayoutCompleteNotification;
	break;
	case ui::AX_EVENT_LOAD_COMPLETE:
	mac_notification = NSAccessibilityLoadCompleteNotification;
	break;
	case ui::AX_EVENT_INVALID_STATUS_CHANGED:
	mac_notification = NSAccessibilityInvalidStatusChangedNotification;
	break;
	case ui::AX_EVENT_SELECTED_CHILDREN_CHANGED:
	if (node->GetRole() == ui::AX_ROLE_GRID \|\|
	node->GetRole() == ui::AX_ROLE_TABLE) {
	mac_notification = NSAccessibilitySelectedRowsChangedNotification;
	} else {
	mac_notification = NSAccessibilitySelectedChildrenChangedNotification;
	}
	break;
	case ui::AX_EVENT_DOCUMENT_SELECTION_CHANGED: {
	mac_notification = NSAccessibilitySelectedTextChangedNotification;
	// WebKit fires a notification both on the focused object and the root.
	BrowserAccessibility* focus = GetFocus();
	if (!focus)
	break; // Just fire a notification on the root.
	NSAccessibilityPostNotification(ToBrowserAccessibilityCocoa(focus),
	mac_notification);

	if (base::mac::IsOSElCapitanOrLater()) {
	// \|NSAccessibilityPostNotificationWithUserInfo\| should be used on OS X
	// 10.11 or later to notify Voiceover about text selection changes. This
	// API has been present on versions of OS X since 10.7 but doesn't
	// appear to be needed by Voiceover before version 10.11.
	NSDictionary* user_info =
	GetUserInfoForSelectedTextChangedNotification();

	BrowserAccessibility* root = GetRoot();
	if (!root)
	return;

	NSAccessibilityPostNotificationWithUserInfo(
	ToBrowserAccessibilityCocoa(focus), mac_notification, user_info);
	NSAccessibilityPostNotificationWithUserInfo(
	ToBrowserAccessibilityCocoa(root), mac_notification, user_info);
	return;
	}
	break;
	}
	case ui::AX_EVENT_CHECKED_STATE_CHANGED:
	mac_notification = NSAccessibilityValueChangedNotification;
	break;
	case ui::AX_EVENT_VALUE_CHANGED:
	mac_notification = NSAccessibilityValueChangedNotification;
	if (base::mac::IsOSElCapitanOrLater() && text_edits_.size()) {
	// It seems that we don't need to distinguish between deleted and
	// inserted text for now.
	base::string16 deleted_text;
	base::string16 inserted_text;
	int32_t id = node->GetId();
	const auto iterator = text_edits_.find(id);
	if (iterator != text_edits_.end())
	inserted_text = iterator->second;
	NSDictionary* user_info = GetUserInfoForValueChangedNotification(
	native_node, deleted_text, inserted_text);

	BrowserAccessibility* root = GetRoot();
	if (!root)
	return;

	NSAccessibilityPostNotificationWithUserInfo(
	native_node, mac_notification, user_info);
	NSAccessibilityPostNotificationWithUserInfo(
	ToBrowserAccessibilityCocoa(root), mac_notification, user_info);
	return;
	}
	break;
	// TODO(nektar): Need to add an event for live region created.
	case ui::AX_EVENT_LIVE_REGION_CHANGED:
	mac_notification = NSAccessibilityLiveRegionChangedNotification;
	break;
	case ui::AX_EVENT_ROW_COUNT_CHANGED:
	mac_notification = NSAccessibilityRowCountChangedNotification;
	break;
	case ui::AX_EVENT_ROW_EXPANDED:
	mac_notification = NSAccessibilityRowExpandedNotification;
	break;
	case ui::AX_EVENT_ROW_COLLAPSED:
	mac_notification = NSAccessibilityRowCollapsedNotification;
	break;
	// TODO(nektar): Add events for busy.
	case ui::AX_EVENT_EXPANDED_CHANGED:
	mac_notification = NSAccessibilityExpandedChanged;
	break;
	// TODO(nektar): Support menu open/close notifications.
	case ui::AX_EVENT_MENU_LIST_ITEM_SELECTED:
	mac_notification = NSAccessibilityMenuItemSelectedNotification;
	break;

	// These events are not used on Mac for now.
	case ui::AX_EVENT_ALERT:
	case ui::AX_EVENT_TEXT_CHANGED:
	case ui::AX_EVENT_CHILDREN_CHANGED:
	case ui::AX_EVENT_MENU_LIST_VALUE_CHANGED:
	case ui::AX_EVENT_SCROLL_POSITION_CHANGED:
	case ui::AX_EVENT_SCROLLED_TO_ANCHOR:
	case ui::AX_EVENT_ARIA_ATTRIBUTE_CHANGED:
	case ui::AX_EVENT_LOCATION_CHANGED:
	return;

	// Deprecated events.
	case ui::AX_EVENT_BLUR:
	case ui::AX_EVENT_HIDE:
	case ui::AX_EVENT_HOVER:
	case ui::AX_EVENT_TEXT_SELECTION_CHANGED:
	case ui::AX_EVENT_SHOW:
	return;
	default:
	DLOG(WARNING) << "Unknown accessibility event: " << event_type;
	return;
	}

	NSAccessibilityPostNotification(native_node, mac_notification);
	}

	void BrowserAccessibilityManagerMac::OnAccessibilityEvents(
	const std::vector<AXEventNotificationDetails>& details) {
	text_edits_.clear();
	// Call the base method last as it might delete the tree if it receives an
	// invalid message.
	BrowserAccessibilityManager::OnAccessibilityEvents(details);
	}

	void BrowserAccessibilityManagerMac::OnNodeDataWillChange(
	ui::AXTree* tree,
	const ui::AXNodeData& old_node_data,
	const ui::AXNodeData& new_node_data) {
	BrowserAccessibilityManager::OnNodeDataWillChange(tree, old_node_data,
	new_node_data);

	// Starting from OS X 10.11, if the user has edited some text we need to
	// dispatch the actual text that changed on the value changed notification.
	// We run this code on all OS X versions to get the highest test coverage.
	base::string16 old_text, new_text;
	ui::AXRole role = new_node_data.role;
	if (role == ui::AX_ROLE_COMBO_BOX \|\| role == ui::AX_ROLE_SEARCH_BOX \|\|
	role == ui::AX_ROLE_TEXT_FIELD) {
	old_text = old_node_data.GetString16Attribute(ui::AX_ATTR_VALUE);
	new_text = new_node_data.GetString16Attribute(ui::AX_ATTR_VALUE);
	} else if (new_node_data.state & (1 << ui::AX_STATE_EDITABLE)) {
	old_text = old_node_data.GetString16Attribute(ui::AX_ATTR_NAME);
	new_text = new_node_data.GetString16Attribute(ui::AX_ATTR_NAME);
	}

	if ((old_text.empty() && new_text.empty()) \|\|
	old_text.length() == new_text.length()) {
	return;
	}

	if (old_text.length() < new_text.length()) {
	// Insertion.
	size_t i = 0;
	while (i < old_text.length() && i < new_text.length() &&
	old_text[i] == new_text[i]) {
	++i;
	}
	size_t length = (new_text.length() - i) - (old_text.length() - i);
	base::string16 inserted_text = new_text.substr(i, length);
	text_edits_[new_node_data.id] = inserted_text;
	} else {
	// Deletion.
	size_t i = 0;
	while (i < old_text.length() && i < new_text.length() &&
	old_text[i] == new_text[i]) {
	++i;
	}
	size_t length = (old_text.length() - i) - (new_text.length() - i);
	base::string16 deleted_text = old_text.substr(i, length);
	text_edits_[new_node_data.id] = deleted_text;
	}
	}

	void BrowserAccessibilityManagerMac::OnAtomicUpdateFinished(
	ui::AXTree* tree,
	bool root_changed,
	const std::vector<ui::AXTreeDelegate::Change>& changes) {
	BrowserAccessibilityManager::OnAtomicUpdateFinished(
	tree, root_changed, changes);

	bool created_live_region = false;
	for (size_t i = 0; i < changes.size(); ++i) {
	if (changes[i].type != NODE_CREATED && changes[i].type != SUBTREE_CREATED)
	continue;

	const ui::AXNode* changed_node = changes[i].node;
	DCHECK(changed_node);
	BrowserAccessibility* obj = GetFromAXNode(changed_node);
	if (obj && obj->HasStringAttribute(ui::AX_ATTR_LIVE_STATUS)) {
	created_live_region = true;
	break;
	}
	}

	if (!created_live_region)
	return;

	// This code is to work around a bug in VoiceOver, where a new live
	// region that gets added is ignored. VoiceOver seems to only scan the
	// page for live regions once. By recreating the NSAccessibility
	// object for the root of the tree, we force VoiceOver to clear out its
	// internal state and find newly-added live regions this time.
	BrowserAccessibilityMac* root =
	static_cast<BrowserAccessibilityMac*>(GetRoot());
	if (root) {
	root->RecreateNativeObject();
	NotifyAccessibilityEvent(
	BrowserAccessibilityEvent::FromTreeChange,
	ui::AX_EVENT_CHILDREN_CHANGED,
	root);
	}
	}

	NSDictionary* BrowserAccessibilityManagerMac::
	GetUserInfoForSelectedTextChangedNotification() {
	NSMutableDictionary* user_info = [[[NSMutableDictionary alloc] init]
	autorelease];
	[user_info setObject:@YES forKey:NSAccessibilityTextStateSyncKey];
	[user_info setObject:@(AXTextStateChangeTypeUnknown)
	forKey:NSAccessibilityTextStateChangeTypeKey];
	[user_info setObject:@(AXTextSelectionDirectionUnknown)
	forKey:NSAccessibilityTextSelectionDirection];
	[user_info setObject:@(AXTextSelectionGranularityUnknown)
	forKey:NSAccessibilityTextSelectionGranularity];
	[user_info setObject:@YES forKey:NSAccessibilityTextSelectionChangedFocus];

	int32_t focus_id = GetTreeData().sel_focus_object_id;
	BrowserAccessibility* focus_object = GetFromID(focus_id);
	if (focus_object) {
	focus_object = focus_object->GetClosestPlatformObject();
	auto native_focus_object = ToBrowserAccessibilityCocoa(focus_object);
	if (native_focus_object && [native_focus_object instanceActive]) {
	[user_info setObject:[native_focus_object selectedTextMarkerRange]
	forKey:NSAccessibilitySelectedTextMarkerRangeAttribute];
	[user_info setObject:native_focus_object
	forKey:NSAccessibilityTextChangeElement];
	}
	}

	return user_info;
	}

	NSDictionary*
	BrowserAccessibilityManagerMac::GetUserInfoForValueChangedNotification(
	const BrowserAccessibilityCocoa* native_node,
	const base::string16& deleted_text,
	const base::string16& inserted_text) const {
	DCHECK(native_node);
	if (deleted_text.empty() && inserted_text.empty())
	return nil;

	NSMutableArray* changes = [[[NSMutableArray alloc] init] autorelease];
	if (!deleted_text.empty()) {
	[changes addObject:@{
	NSAccessibilityTextEditType : @(AXTextEditTypeUnknown),
	NSAccessibilityTextChangeValueLength : @(deleted_text.length()),
	NSAccessibilityTextChangeValue : base::SysUTF16ToNSString(deleted_text)
	}];
	}
	if (!inserted_text.empty()) {
	[changes addObject:@{
	NSAccessibilityTextEditType : @(AXTextEditTypeUnknown),
	NSAccessibilityTextChangeValueLength : @(inserted_text.length()),
	NSAccessibilityTextChangeValue : base::SysUTF16ToNSString(inserted_text)
	}];
	}

	return @{
	NSAccessibilityTextStateChangeTypeKey : @(AXTextStateChangeTypeEdit),
	NSAccessibilityTextChangeValues : changes,
	NSAccessibilityTextChangeElement : native_node
	};
	}

	} // namespace content