Schedule bitmap animation timers on the compositor task runner.

third_party/WebKit/Source/core/dom/TaskRunnerHelper.h

 // Copyright 2016 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.
 
 #ifndef TaskRunnerHelper_h
 #define TaskRunnerHelper_h
 
 #include "core/CoreExport.h"
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/HashTraits.h"
@@ skipping 105 matching lines @@
   // may be throttled.
   //
   // UnspecedLoading type should be used for all tasks associated with
   // loading page content, UnspecedTimer should be used for all other purposes.
   kUnspecedTimer,
   kUnspecedLoading,
 
   // Tasks that must not be throttled should be posted here, but the usage
   // should be very limited.
   kUnthrottled,
+
+  // Tasks related to animating images should be posted here.

[Sami, 2017/04/27 17:38:17]

nit: No need to limit this to image animations -- could just say animations in
general.

[Dan Elphick, 2017/05/03 09:41:06]

no longer required

+  kAnimationTimer,
 };
 
 // HashTraits for TaskType.
 struct TaskTypeTraits : WTF::GenericHashTraits<TaskType> {
   static const bool kEmptyValueIsZero = false;
   static TaskType EmptyValue() { return static_cast<TaskType>(-1); }
   static void ConstructDeletedValue(TaskType& slot, bool) {
     slot = static_cast<TaskType>(-2);
   }
   static bool IsDeletedValue(TaskType value) {
@@ skipping 18 matching lines @@
   // scope that corresponds to the given WorkerThread. Note that WorkerThread is
   // a per-global-scope object while the naming might sound differently.
   // TODO(nhiroki): Rename WorkerThread to something that clarifies it's a
   // per-global-scope object.
   static RefPtr<WebTaskRunner> Get(TaskType, WorkerThread*);
 };
 
 }  // namespace blink
 
 #endif