content/browser/theme_helper_mac.mm - chromium/src - Git at Google

 // Copyright 2013 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "content/browser/theme_helper_mac.h"

 #import <Carbon/Carbon.h>
 #import <Cocoa/Cocoa.h>

 #include "base/command_line.h"
 #include "base/containers/span.h"
 #include "base/functional/bind.h"
 #include "base/functional/callback.h"
 #include "base/mac/mac_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/common/renderer.mojom.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_widget_host_iterator.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/content_switches.h"
 #include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"

 using content::RenderProcessHost;
 using content::RenderProcessHostImpl;
 using content::ThemeHelperMac;

 namespace {

 void FillScrollbarThemeParams(
     content::mojom::UpdateScrollbarThemeParams* params) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
   [defaults synchronize];

   // NSScrollerButtonDelay and NSScrollerButtonPeriod are no longer initialized
   // in +[NSApplication _initializeRegisteredDefaults] as of 10.15. Their values
   // still seem to affect behavior, but their use is logged as an "unusual app
   // config", so it's not clear how much longer they'll be implemented.
   params->has_initial_button_delay =
       [defaults objectForKey:@"NSScrollerButtonDelay"] != nil;
   params->initial_button_delay =
       [defaults floatForKey:@"NSScrollerButtonDelay"];
   params->has_autoscroll_button_delay =
       [defaults objectForKey:@"NSScrollerButtonPeriod"] != nil;
   params->autoscroll_button_delay =
       [defaults floatForKey:@"NSScrollerButtonPeriod"];
   params->jump_on_track_click =
       [defaults boolForKey:@"AppleScrollerPagingBehavior"];
   params->preferred_scroller_style =
       static_cast<blink::ScrollerStyle>([NSScroller preferredScrollerStyle]);

   id rubber_band_value = [defaults objectForKey:@"NSScrollViewRubberbanding"];
   params->scroll_view_rubber_banding =
       rubber_band_value ? [rubber_band_value boolValue] : YES;
 }

 void SendSystemColorsChangedMessage(content::mojom::Renderer* renderer) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
   [defaults synchronize];

   renderer->OnSystemColorsChanged(
       [[defaults stringForKey:@"AppleAquaColorVariant"] intValue]);
 }

 SkColor NSColorToSkColor(NSColor* color) {
   NSColor* color_in_color_space =
       [color colorUsingColorSpace:[NSColorSpace sRGBColorSpace]];
   if (color_in_color_space) {
     // Use nextafter() to avoid rounding colors in a way that could be off-by-
     // one. See https://bugs.webkit.org/show_bug.cgi?id=6129.
     static const double kScaleFactor = nextafter(256.0, 0.0);
     return SkColorSetARGB(
         static_cast<int>(kScaleFactor * [color_in_color_space alphaComponent]),
         static_cast<int>(kScaleFactor * [color_in_color_space redComponent]),
         static_cast<int>(kScaleFactor * [color_in_color_space greenComponent]),
         static_cast<int>(kScaleFactor * [color_in_color_space blueComponent]));
   }

   // This conversion above can fail if the NSColor in question is an
   // NSPatternColor (as many system colors are). These colors are actually a
   // repeating pattern not just a solid color. To work around this we simply
   // draw a 1x1 image of the color and use that pixel's color. It might be
   // better to use an average of the colors in the pattern instead.
   base::scoped_nsobject<NSBitmapImageRep> offscreen_rep(
       [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:nil
                                               pixelsWide:1
                                               pixelsHigh:1
                                            bitsPerSample:8
                                          samplesPerPixel:4
                                                 hasAlpha:YES
                                                 isPlanar:NO
                                           colorSpaceName:NSDeviceRGBColorSpace
                                              bytesPerRow:4
                                             bitsPerPixel:32]);

   {
     gfx::ScopedNSGraphicsContextSaveGState gstate;
     [NSGraphicsContext
         setCurrentContext:[NSGraphicsContext
                               graphicsContextWithBitmapImageRep:offscreen_rep]];
     [color set];
     NSRectFill(NSMakeRect(0, 0, 1, 1));
   }

   NSUInteger pixel[4];
   [offscreen_rep getPixel:pixel atX:0 y:0];
   // This recursive call will not recurse again, because the color space
   // the second time around is NSDeviceRGBColorSpace.
   return NSColorToSkColor([NSColor colorWithDeviceRed:pixel[0] / 255.
                                                 green:pixel[1] / 255.
                                                  blue:pixel[2] / 255.
                                                 alpha:1.]);
 }

 } // namespace

 @interface SystemThemeObserver : NSObject {
   base::RepeatingClosure _colorsChangedCallback;
 }

 - (instancetype)initWithColorsChangedCallback:
     (base::RepeatingClosure)colorsChangedCallback;
 - (void)appearancePrefsChanged:(NSNotification*)notification;
 - (void)behaviorPrefsChanged:(NSNotification*)notification;
 - (void)notifyPrefsChangedWithRedraw:(BOOL)redraw;

 @end

 @implementation SystemThemeObserver

 - (instancetype)initWithColorsChangedCallback:
     (base::RepeatingClosure)colorsChangedCallback {
   if (!(self = [super init])) {
     return nil;
   }

   _colorsChangedCallback = std::move(colorsChangedCallback);

   NSDistributedNotificationCenter* distributedCenter =
       [NSDistributedNotificationCenter defaultCenter];
   [distributedCenter addObserver:self
                         selector:@selector(appearancePrefsChanged:)
                             name:@"AppleAquaScrollBarVariantChanged"
                           object:nil
                suspensionBehavior:
                    NSNotificationSuspensionBehaviorDeliverImmediately];

   [distributedCenter addObserver:self
                         selector:@selector(behaviorPrefsChanged:)
                             name:@"AppleNoRedisplayAppearancePreferenceChanged"
                           object:nil
               suspensionBehavior:NSNotificationSuspensionBehaviorCoalesce];

   [distributedCenter addObserver:self
                         selector:@selector(behaviorPrefsChanged:)
                             name:@"NSScrollAnimationEnabled"
                           object:nil
               suspensionBehavior:NSNotificationSuspensionBehaviorCoalesce];

   [distributedCenter addObserver:self
                         selector:@selector(appearancePrefsChanged:)
                             name:@"AppleScrollBarVariant"
                           object:nil
               suspensionBehavior:
                   NSNotificationSuspensionBehaviorDeliverImmediately];

   [distributedCenter
              addObserver:self
                 selector:@selector(behaviorPrefsChanged:)
                     name:@"NSScrollViewRubberbanding"
                   object:nil
       suspensionBehavior:NSNotificationSuspensionBehaviorDeliverImmediately];

   // In single-process mode, renderers will catch these notifications
   // themselves and listening for them here may trigger the DCHECK in Observe().
   if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kSingleProcess)) {
     NSNotificationCenter* center = [NSNotificationCenter defaultCenter];

     [center addObserver:self
                selector:@selector(behaviorPrefsChanged:)
                    name:NSPreferredScrollerStyleDidChangeNotification
                  object:nil];

     [center addObserver:self
                selector:@selector(systemColorsChanged:)
                    name:NSSystemColorsDidChangeNotification
                  object:nil];
   }

   return self;
 }

 - (void)dealloc {
   [[NSDistributedNotificationCenter defaultCenter] removeObserver:self];
   [super dealloc];
 }

 - (void)appearancePrefsChanged:(NSNotification*)notification {
   [self notifyPrefsChangedWithRedraw:YES];
 }

 - (void)behaviorPrefsChanged:(NSNotification*)notification {
   [self notifyPrefsChangedWithRedraw:NO];
 }

 - (void)systemColorsChanged:(NSNotification*)notification {
   _colorsChangedCallback.Run();

   for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
        !it.IsAtEnd();
        it.Advance()) {
     SendSystemColorsChangedMessage(
         it.GetCurrentValue()->GetRendererInterface());
   }
 }

 - (void)notifyPrefsChangedWithRedraw:(BOOL)redraw {
   for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
        !it.IsAtEnd();
        it.Advance()) {
     content::mojom::UpdateScrollbarThemeParamsPtr params =
         content::mojom::UpdateScrollbarThemeParams::New();
     FillScrollbarThemeParams(params.get());
     params->redraw = redraw;
     RenderProcessHostImpl* process_host =
         static_cast<RenderProcessHostImpl*>(it.GetCurrentValue());
     process_host->GetRendererInterface()->UpdateScrollbarTheme(
         std::move(params));
   }

   std::unique_ptr<content::RenderWidgetHostIterator> all_widgets(
       content::RenderWidgetHostImpl::GetAllRenderWidgetHosts());
   while (content::RenderWidgetHost* widget = all_widgets->GetNextHost()) {
     content::RenderViewHost* rvh = content::RenderViewHost::From(widget);
     if (!rvh)
       continue;

     content::WebContents::FromRenderViewHost(rvh)->OnWebPreferencesChanged();
   }
 }

 @end

 namespace content {

 struct ThemeHelperMac::ObjCStorage {
   // ObjC object that observes notifications from the system.
   base::scoped_nsobject<SystemThemeObserver> theme_observer_;
 };

 // static
 ThemeHelperMac* ThemeHelperMac::GetInstance() {
   static ThemeHelperMac* instance = new ThemeHelperMac();
   return instance;
 }

 base::ReadOnlySharedMemoryRegion
 ThemeHelperMac::DuplicateReadOnlyColorMapRegion() {
   return read_only_color_map_.Duplicate();
 }

 ThemeHelperMac::ThemeHelperMac()
     : objc_storage_(std::make_unique<ObjCStorage>()) {
   // Allocate a region for the SkColor value table and map it.
   auto writable_region = base::WritableSharedMemoryRegion::Create(
       sizeof(SkColor) * blink::kMacSystemColorIDCount *
       blink::kMacSystemColorSchemeCount);
   writable_color_map_ = writable_region.Map();

   // Downgrade the region to read-only after it has been mapped.
   read_only_color_map_ = base::WritableSharedMemoryRegion::ConvertToReadOnly(
       std::move(writable_region));

   // Store the current color scheme into the table.
   LoadSystemColors();

   // Start observing for changes.
   objc_storage_->theme_observer_.reset([[SystemThemeObserver alloc]
       initWithColorsChangedCallback:base::BindRepeating(
                                         &ThemeHelperMac::LoadSystemColors,
                                         base::Unretained(this))]);
 }

 ThemeHelperMac::~ThemeHelperMac() = default;

 void ThemeHelperMac::LoadSystemColorsForCurrentAppearance(
     base::span<SkColor> values) {
   for (size_t i = 0; i < blink::kMacSystemColorIDCount; ++i) {
     blink::MacSystemColorID color_id = static_cast<blink::MacSystemColorID>(i);
     switch (color_id) {
       case blink::MacSystemColorID::kControlAccentBlueColor: {
         NSColor* color =
             [NSColor colorWithCatalogName:@"System"
                                 colorName:@"controlAccentBlueColor"];
         if (color) {
           values[i] = NSColorToSkColor(color);
         } else {
           // If the controlAccentBlueColor isn't available just set a black
           // value.
           values[i] = SK_ColorBLACK;
         }
         break;
       }
       case blink::MacSystemColorID::kControlAccentColor:
         if (@available(macOS 10.14, *)) {
           values[i] = NSColorToSkColor(NSColor.controlAccentColor);
         } else {
           // controlAccentColor property is not available before macOS 10.14,
           // so keyboardFocusIndicatorColor is used instead.
           values[i] = NSColorToSkColor(NSColor.keyboardFocusIndicatorColor);
         }
         break;
       case blink::MacSystemColorID::kKeyboardFocusIndicator:
         values[i] = NSColorToSkColor(NSColor.keyboardFocusIndicatorColor);
         break;
       case blink::MacSystemColorID::kSecondarySelectedControl:
         if (@available(macOS 10.14, *)) {
           values[i] = NSColorToSkColor(
               NSColor.unemphasizedSelectedContentBackgroundColor);
         } else {
           values[i] = NSColorToSkColor(NSColor.secondarySelectedControlColor);
         }
         break;
       case blink::MacSystemColorID::kSelectedTextBackground:
         values[i] = NSColorToSkColor(NSColor.selectedTextBackgroundColor);
         break;
       case blink::MacSystemColorID::kCount:
         NOTREACHED();
         break;
     }
   }
 }

 void ThemeHelperMac::LoadSystemColors() {
   static_assert(blink::kMacSystemColorSchemeCount == 2,
                 "Light and dark color scheme system colors loaded.");
   base::span<SkColor> values = writable_color_map_.GetMemoryAsSpan<SkColor>(
       blink::kMacSystemColorIDCount * blink::kMacSystemColorSchemeCount);

   if (@available(macOS 11, *)) {
     [[NSAppearance appearanceNamed:NSAppearanceNameAqua]
         performAsCurrentDrawingAppearance:^{
           LoadSystemColorsForCurrentAppearance(values.subspan(
               0, static_cast<size_t>(blink::MacSystemColorID::kCount)));
         }];
     [[NSAppearance appearanceNamed:NSAppearanceNameDarkAqua]
         performAsCurrentDrawingAppearance:^{
           LoadSystemColorsForCurrentAppearance(values.subspan(
               static_cast<size_t>(blink::MacSystemColorID::kCount),
               static_cast<size_t>(blink::MacSystemColorID::kCount)));
         }];
   } else if (@available(macOS 10.14, *)) {
     NSAppearance* saved_appearance = NSAppearance.currentAppearance;
     NSAppearance.currentAppearance =
         [NSAppearance appearanceNamed:NSAppearanceNameAqua];
     LoadSystemColorsForCurrentAppearance(values.subspan(
         0, static_cast<size_t>(blink::MacSystemColorID::kCount)));
     NSAppearance.currentAppearance =
         [NSAppearance appearanceNamed:NSAppearanceNameDarkAqua];
     LoadSystemColorsForCurrentAppearance(
         values.subspan(static_cast<size_t>(blink::MacSystemColorID::kCount),
                        static_cast<size_t>(blink::MacSystemColorID::kCount)));
     NSAppearance.currentAppearance = saved_appearance;
   } else {
     LoadSystemColorsForCurrentAppearance(values.subspan(
         0, static_cast<size_t>(blink::MacSystemColorID::kCount)));
     LoadSystemColorsForCurrentAppearance(
         values.subspan(static_cast<size_t>(blink::MacSystemColorID::kCount),
                        static_cast<size_t>(blink::MacSystemColorID::kCount)));
   }
 }

 void ThemeHelperMac::OnRenderProcessHostCreated(
     content::RenderProcessHost* host) {
   // When a new RenderProcess is created, send it the initial preference
   // parameters.
   content::mojom::UpdateScrollbarThemeParamsPtr params =
       content::mojom::UpdateScrollbarThemeParams::New();
   FillScrollbarThemeParams(params.get());
   params->redraw = false;

   RenderProcessHostImpl* process_host =
       static_cast<content::RenderProcessHostImpl*>(host);
   content::mojom::Renderer* renderer = process_host->GetRendererInterface();
   renderer->UpdateScrollbarTheme(std::move(params));
   SendSystemColorsChangedMessage(renderer);
 }

 }  // namespace content
	// Copyright 2013 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "content/browser/theme_helper_mac.h"

	#import <Carbon/Carbon.h>
	#import <Cocoa/Cocoa.h>

	#include "base/command_line.h"
	#include "base/containers/span.h"
	#include "base/functional/bind.h"
	#include "base/functional/callback.h"
	#include "base/mac/mac_util.h"
	#include "base/mac/scoped_nsobject.h"
	#include "base/strings/sys_string_conversions.h"
	#include "content/browser/renderer_host/render_process_host_impl.h"
	#include "content/browser/renderer_host/render_widget_host_impl.h"
	#include "content/common/renderer.mojom.h"
	#include "content/public/browser/browser_thread.h"
	#include "content/public/browser/notification_service.h"
	#include "content/public/browser/notification_types.h"
	#include "content/public/browser/render_process_host.h"
	#include "content/public/browser/render_view_host.h"
	#include "content/public/browser/render_widget_host_iterator.h"
	#include "content/public/browser/web_contents.h"
	#include "content/public/common/content_switches.h"
	#include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"

	using content::RenderProcessHost;
	using content::RenderProcessHostImpl;
	using content::ThemeHelperMac;

	namespace {

	void FillScrollbarThemeParams(
	content::mojom::UpdateScrollbarThemeParams* params) {
	DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

	NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
	[defaults synchronize];

	// NSScrollerButtonDelay and NSScrollerButtonPeriod are no longer initialized
	// in +[NSApplication _initializeRegisteredDefaults] as of 10.15. Their values
	// still seem to affect behavior, but their use is logged as an "unusual app
	// config", so it's not clear how much longer they'll be implemented.
	params->has_initial_button_delay =
	[defaults objectForKey:@"NSScrollerButtonDelay"] != nil;
	params->initial_button_delay =
	[defaults floatForKey:@"NSScrollerButtonDelay"];
	params->has_autoscroll_button_delay =
	[defaults objectForKey:@"NSScrollerButtonPeriod"] != nil;
	params->autoscroll_button_delay =
	[defaults floatForKey:@"NSScrollerButtonPeriod"];
	params->jump_on_track_click =
	[defaults boolForKey:@"AppleScrollerPagingBehavior"];
	params->preferred_scroller_style =
	static_cast<blink::ScrollerStyle>([NSScroller preferredScrollerStyle]);

	id rubber_band_value = [defaults objectForKey:@"NSScrollViewRubberbanding"];
	params->scroll_view_rubber_banding =
	rubber_band_value ? [rubber_band_value boolValue] : YES;
	}

	void SendSystemColorsChangedMessage(content::mojom::Renderer* renderer) {
	DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

	NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
	[defaults synchronize];

	renderer->OnSystemColorsChanged(
	[[defaults stringForKey:@"AppleAquaColorVariant"] intValue]);
	}

	SkColor NSColorToSkColor(NSColor* color) {
	NSColor* color_in_color_space =
	[color colorUsingColorSpace:[NSColorSpace sRGBColorSpace]];
	if (color_in_color_space) {
	// Use nextafter() to avoid rounding colors in a way that could be off-by-
	// one. See https://bugs.webkit.org/show_bug.cgi?id=6129.
	static const double kScaleFactor = nextafter(256.0, 0.0);
	return SkColorSetARGB(
	static_cast<int>(kScaleFactor * [color_in_color_space alphaComponent]),
	static_cast<int>(kScaleFactor * [color_in_color_space redComponent]),
	static_cast<int>(kScaleFactor * [color_in_color_space greenComponent]),
	static_cast<int>(kScaleFactor * [color_in_color_space blueComponent]));
	}

	// This conversion above can fail if the NSColor in question is an
	// NSPatternColor (as many system colors are). These colors are actually a
	// repeating pattern not just a solid color. To work around this we simply
	// draw a 1x1 image of the color and use that pixel's color. It might be
	// better to use an average of the colors in the pattern instead.
	base::scoped_nsobject<NSBitmapImageRep> offscreen_rep(
	[[NSBitmapImageRep alloc] initWithBitmapDataPlanes:nil
	pixelsWide:1
	pixelsHigh:1
	bitsPerSample:8
	samplesPerPixel:4
	hasAlpha:YES
	isPlanar:NO
	colorSpaceName:NSDeviceRGBColorSpace
	bytesPerRow:4
	bitsPerPixel:32]);

	{
	gfx::ScopedNSGraphicsContextSaveGState gstate;
	[NSGraphicsContext
	setCurrentContext:[NSGraphicsContext
	graphicsContextWithBitmapImageRep:offscreen_rep]];
	[color set];
	NSRectFill(NSMakeRect(0, 0, 1, 1));
	}

	NSUInteger pixel[4];
	[offscreen_rep getPixel:pixel atX:0 y:0];
	// This recursive call will not recurse again, because the color space
	// the second time around is NSDeviceRGBColorSpace.
	return NSColorToSkColor([NSColor colorWithDeviceRed:pixel[0] / 255.
	green:pixel[1] / 255.
	blue:pixel[2] / 255.
	alpha:1.]);
	}

	} // namespace

	@interface SystemThemeObserver : NSObject {
	base::RepeatingClosure _colorsChangedCallback;
	}

	- (instancetype)initWithColorsChangedCallback:
	(base::RepeatingClosure)colorsChangedCallback;
	- (void)appearancePrefsChanged:(NSNotification*)notification;
	- (void)behaviorPrefsChanged:(NSNotification*)notification;
	- (void)notifyPrefsChangedWithRedraw:(BOOL)redraw;

	@end

	@implementation SystemThemeObserver

	- (instancetype)initWithColorsChangedCallback:
	(base::RepeatingClosure)colorsChangedCallback {
	if (!(self = [super init])) {
	return nil;
	}

	_colorsChangedCallback = std::move(colorsChangedCallback);

	NSDistributedNotificationCenter* distributedCenter =
	[NSDistributedNotificationCenter defaultCenter];
	[distributedCenter addObserver:self
	selector:@selector(appearancePrefsChanged:)
	name:@"AppleAquaScrollBarVariantChanged"
	object:nil
	suspensionBehavior:
	NSNotificationSuspensionBehaviorDeliverImmediately];

	[distributedCenter addObserver:self
	selector:@selector(behaviorPrefsChanged:)
	name:@"AppleNoRedisplayAppearancePreferenceChanged"
	object:nil
	suspensionBehavior:NSNotificationSuspensionBehaviorCoalesce];

	[distributedCenter addObserver:self
	selector:@selector(behaviorPrefsChanged:)
	name:@"NSScrollAnimationEnabled"
	object:nil
	suspensionBehavior:NSNotificationSuspensionBehaviorCoalesce];

	[distributedCenter addObserver:self
	selector:@selector(appearancePrefsChanged:)
	name:@"AppleScrollBarVariant"
	object:nil
	suspensionBehavior:
	NSNotificationSuspensionBehaviorDeliverImmediately];

	[distributedCenter
	addObserver:self
	selector:@selector(behaviorPrefsChanged:)
	name:@"NSScrollViewRubberbanding"
	object:nil
	suspensionBehavior:NSNotificationSuspensionBehaviorDeliverImmediately];

	// In single-process mode, renderers will catch these notifications
	// themselves and listening for them here may trigger the DCHECK in Observe().
	if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
	switches::kSingleProcess)) {
	NSNotificationCenter* center = [NSNotificationCenter defaultCenter];

	[center addObserver:self
	selector:@selector(behaviorPrefsChanged:)
	name:NSPreferredScrollerStyleDidChangeNotification
	object:nil];

	[center addObserver:self
	selector:@selector(systemColorsChanged:)
	name:NSSystemColorsDidChangeNotification
	object:nil];
	}

	return self;
	}

	- (void)dealloc {
	[[NSDistributedNotificationCenter defaultCenter] removeObserver:self];
	[super dealloc];
	}

	- (void)appearancePrefsChanged:(NSNotification*)notification {
	[self notifyPrefsChangedWithRedraw:YES];
	}

	- (void)behaviorPrefsChanged:(NSNotification*)notification {
	[self notifyPrefsChangedWithRedraw:NO];
	}

	- (void)systemColorsChanged:(NSNotification*)notification {
	_colorsChangedCallback.Run();

	for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
	!it.IsAtEnd();
	it.Advance()) {
	SendSystemColorsChangedMessage(
	it.GetCurrentValue()->GetRendererInterface());
	}
	}

	- (void)notifyPrefsChangedWithRedraw:(BOOL)redraw {
	for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
	!it.IsAtEnd();
	it.Advance()) {
	content::mojom::UpdateScrollbarThemeParamsPtr params =
	content::mojom::UpdateScrollbarThemeParams::New();
	FillScrollbarThemeParams(params.get());
	params->redraw = redraw;
	RenderProcessHostImpl* process_host =
	static_cast<RenderProcessHostImpl*>(it.GetCurrentValue());
	process_host->GetRendererInterface()->UpdateScrollbarTheme(
	std::move(params));
	}

	std::unique_ptr<content::RenderWidgetHostIterator> all_widgets(
	content::RenderWidgetHostImpl::GetAllRenderWidgetHosts());
	while (content::RenderWidgetHost* widget = all_widgets->GetNextHost()) {
	content::RenderViewHost* rvh = content::RenderViewHost::From(widget);
	if (!rvh)
	continue;

	content::WebContents::FromRenderViewHost(rvh)->OnWebPreferencesChanged();
	}
	}

	@end

	namespace content {

	struct ThemeHelperMac::ObjCStorage {
	// ObjC object that observes notifications from the system.
	base::scoped_nsobject<SystemThemeObserver> theme_observer_;
	};

	// static
	ThemeHelperMac* ThemeHelperMac::GetInstance() {
	static ThemeHelperMac* instance = new ThemeHelperMac();
	return instance;
	}

	base::ReadOnlySharedMemoryRegion
	ThemeHelperMac::DuplicateReadOnlyColorMapRegion() {
	return read_only_color_map_.Duplicate();
	}

	ThemeHelperMac::ThemeHelperMac()
	: objc_storage_(std::make_unique<ObjCStorage>()) {
	// Allocate a region for the SkColor value table and map it.
	auto writable_region = base::WritableSharedMemoryRegion::Create(
	sizeof(SkColor) * blink::kMacSystemColorIDCount *
	blink::kMacSystemColorSchemeCount);
	writable_color_map_ = writable_region.Map();

	// Downgrade the region to read-only after it has been mapped.
	read_only_color_map_ = base::WritableSharedMemoryRegion::ConvertToReadOnly(
	std::move(writable_region));

	// Store the current color scheme into the table.
	LoadSystemColors();

	// Start observing for changes.
	objc_storage_->theme_observer_.reset([[SystemThemeObserver alloc]
	initWithColorsChangedCallback:base::BindRepeating(
	&ThemeHelperMac::LoadSystemColors,
	base::Unretained(this))]);
	}

	ThemeHelperMac::~ThemeHelperMac() = default;

	void ThemeHelperMac::LoadSystemColorsForCurrentAppearance(
	base::span<SkColor> values) {
	for (size_t i = 0; i < blink::kMacSystemColorIDCount; ++i) {
	blink::MacSystemColorID color_id = static_cast<blink::MacSystemColorID>(i);
	switch (color_id) {
	case blink::MacSystemColorID::kControlAccentBlueColor: {
	NSColor* color =
	[NSColor colorWithCatalogName:@"System"
	colorName:@"controlAccentBlueColor"];
	if (color) {
	values[i] = NSColorToSkColor(color);
	} else {
	// If the controlAccentBlueColor isn't available just set a black
	// value.
	values[i] = SK_ColorBLACK;
	}
	break;
	}
	case blink::MacSystemColorID::kControlAccentColor:
	if (@available(macOS 10.14, *)) {
	values[i] = NSColorToSkColor(NSColor.controlAccentColor);
	} else {
	// controlAccentColor property is not available before macOS 10.14,
	// so keyboardFocusIndicatorColor is used instead.
	values[i] = NSColorToSkColor(NSColor.keyboardFocusIndicatorColor);
	}
	break;
	case blink::MacSystemColorID::kKeyboardFocusIndicator:
	values[i] = NSColorToSkColor(NSColor.keyboardFocusIndicatorColor);
	break;
	case blink::MacSystemColorID::kSecondarySelectedControl:
	if (@available(macOS 10.14, *)) {
	values[i] = NSColorToSkColor(
	NSColor.unemphasizedSelectedContentBackgroundColor);
	} else {
	values[i] = NSColorToSkColor(NSColor.secondarySelectedControlColor);
	}
	break;
	case blink::MacSystemColorID::kSelectedTextBackground:
	values[i] = NSColorToSkColor(NSColor.selectedTextBackgroundColor);
	break;
	case blink::MacSystemColorID::kCount:
	NOTREACHED();
	break;
	}
	}
	}

	void ThemeHelperMac::LoadSystemColors() {
	static_assert(blink::kMacSystemColorSchemeCount == 2,
	"Light and dark color scheme system colors loaded.");
	base::span<SkColor> values = writable_color_map_.GetMemoryAsSpan<SkColor>(
	blink::kMacSystemColorIDCount * blink::kMacSystemColorSchemeCount);

	if (@available(macOS 11, *)) {
	[[NSAppearance appearanceNamed:NSAppearanceNameAqua]
	performAsCurrentDrawingAppearance:^{
	LoadSystemColorsForCurrentAppearance(values.subspan(
	0, static_cast<size_t>(blink::MacSystemColorID::kCount)));
	}];
	[[NSAppearance appearanceNamed:NSAppearanceNameDarkAqua]
	performAsCurrentDrawingAppearance:^{
	LoadSystemColorsForCurrentAppearance(values.subspan(
	static_cast<size_t>(blink::MacSystemColorID::kCount),
	static_cast<size_t>(blink::MacSystemColorID::kCount)));
	}];
	} else if (@available(macOS 10.14, *)) {
	NSAppearance* saved_appearance = NSAppearance.currentAppearance;
	NSAppearance.currentAppearance =
	[NSAppearance appearanceNamed:NSAppearanceNameAqua];
	LoadSystemColorsForCurrentAppearance(values.subspan(
	0, static_cast<size_t>(blink::MacSystemColorID::kCount)));
	NSAppearance.currentAppearance =
	[NSAppearance appearanceNamed:NSAppearanceNameDarkAqua];
	LoadSystemColorsForCurrentAppearance(
	values.subspan(static_cast<size_t>(blink::MacSystemColorID::kCount),
	static_cast<size_t>(blink::MacSystemColorID::kCount)));
	NSAppearance.currentAppearance = saved_appearance;
	} else {
	LoadSystemColorsForCurrentAppearance(values.subspan(
	0, static_cast<size_t>(blink::MacSystemColorID::kCount)));
	LoadSystemColorsForCurrentAppearance(
	values.subspan(static_cast<size_t>(blink::MacSystemColorID::kCount),
	static_cast<size_t>(blink::MacSystemColorID::kCount)));
	}
	}

	void ThemeHelperMac::OnRenderProcessHostCreated(
	content::RenderProcessHost* host) {
	// When a new RenderProcess is created, send it the initial preference
	// parameters.
	content::mojom::UpdateScrollbarThemeParamsPtr params =
	content::mojom::UpdateScrollbarThemeParams::New();
	FillScrollbarThemeParams(params.get());
	params->redraw = false;

	RenderProcessHostImpl* process_host =
	static_cast<content::RenderProcessHostImpl*>(host);
	content::mojom::Renderer* renderer = process_host->GetRendererInterface();
	renderer->UpdateScrollbarTheme(std::move(params));
	SendSystemColorsChangedMessage(renderer);
	}

	} // namespace content