Schedule bitmap animation timers on the compositor task runner.

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

 // Copyright 2014 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 "platform/scheduler/renderer/renderer_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/debug/stack_trace.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 1061 matching lines @@
     case UseCase::TOUCHSTART:
       new_policy.rail_mode = v8::PERFORMANCE_RESPONSE;
       new_policy.compositor_queue_policy.priority = TaskQueue::HIGH_PRIORITY;
       new_policy.loading_queue_policy.is_enabled = false;
       new_policy.timer_queue_policy.is_enabled = false;
       // NOTE this is a nop due to the above.
       expensive_task_policy = ExpensiveTaskPolicy::BLOCK;
       break;
 
     case UseCase::NONE:
+      new_policy.compositor_queue_policy.priority =
+          main_thread_compositing_is_fast ? TaskQueue::HIGH_PRIORITY
+                                          : TaskQueue::NORMAL_PRIORITY;
+
       // It's only safe to block tasks that if we are expecting a compositor
       // driven gesture.
       if (touchstart_expected_soon &&
           GetAnyThread().last_gesture_was_compositor_driven) {
         new_policy.rail_mode = v8::PERFORMANCE_RESPONSE;
         expensive_task_policy = ExpensiveTaskPolicy::BLOCK;
       }
       break;
 
     case UseCase::LOADING:
@@ skipping 905 matching lines @@
     case TimeDomainType::VIRTUAL:
       return "virtual";
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink