| // Copyright 2015 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_PLUGIN_SCRIPT_FORBIDDEN_SCOPE_H_ |
| #define THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_PLUGIN_SCRIPT_FORBIDDEN_SCOPE_H_ |
| |
| #include "third_party/blink/renderer/core/core_export.h" |
| #include "third_party/blink/renderer/platform/wtf/allocator/allocator.h" |
| |
| namespace blink { |
| |
| // Similar to ScriptForbiddenScope, but more selective. This is intended to help |
| // reduce the number of places where Flash can run a nested run loop as its |
| // plugin element is being destroyed. One of the reasons that Flash runs this |
| // nested run loop is to allow Flash content to synchronously script the |
| // page when the plugin element is destroyed. |
| // |
| // This is problematic for many reasons: the DOM may not be in a consistent |
| // state, since Blink is in the middle of detaching nodes, nested run loops |
| // can cause normally impossible conditions to occur (https://crbug.com/367210), |
| // etc. |
| // |
| // When this object is instantiated on the stack, it allows execution of event |
| // handlers, etc but blocks attempts by plugins to call back into Blink to |
| // execute script. |
| // |
| // Background: |
| // For historical reasons, Flash has allowed synchronous scripting during |
| // teardown of the plugin. This is generally problematic, but sites apparently |
| // rely on this behavior. Over time, Blink has added restrictions on this |
| // synchronous scripting: for example, past a certain point in Frame detach, |
| // script execution by Flash is ignored: https://crbug.com/371084. |
| // |
| // Unfortunately, there are still ways for plugins to synchronously script |
| // during Document detach: if an unload handler removes a Flash plugin element, |
| // that will run the nested run loop, etc. This scoper is intended to block |
| // those usages, with the eventual goal that Frame detach will never have to run |
| // a nested run loop. |
| class CORE_EXPORT PluginScriptForbiddenScope final { |
| STACK_ALLOCATED(); |
| |
| public: |
| PluginScriptForbiddenScope(); |
| PluginScriptForbiddenScope(const PluginScriptForbiddenScope&) = delete; |
| PluginScriptForbiddenScope& operator=(const PluginScriptForbiddenScope&) = |
| delete; |
| ~PluginScriptForbiddenScope(); |
| |
| static bool IsForbidden(); |
| }; |
| |
| } // namespace blink |
| |
| #endif // THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_PLUGIN_SCRIPT_FORBIDDEN_SCOPE_H_ |