Reland "Throttle resource message requests during user interaction"

content/renderer/scheduler/renderer_scheduler.h

 // 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.
 
 #ifndef CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_H_
 #define CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_H_
 
 #include "content/renderer/scheduler/single_thread_idle_task_runner.h"
 #include "content/renderer/scheduler/task_queue_manager.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
@@ skipping 31 matching lines @@
 
   // Tells the scheduler that the system received an input event. Called by the
   // compositor (impl) thread.
   virtual void DidReceiveInputEventOnCompositorThread(
       blink::WebInputEvent::Type type) = 0;
 
   // Tells the scheduler that the system is displaying an input animation (e.g.
   // a fling). Called by the compositor (impl) thread.
   virtual void DidAnimateForInputOnCompositorThread() = 0;
 
+  // Returns true if the scheduler has reason to believe that high priority work
+  // may soon arrive on the main thread, e.g., if gesture events were observed
+  // recently.
+  // Must be called from the main thread.
+  virtual bool ShouldAnticipateHighPriorityWork() = 0;
+
   // Returns true if there is high priority work pending on the main thread
-  // and the caller should yield to let the scheduler service that work.
+  // and the caller should yield to let the scheduler service that work. Note
+  // that this is a stricter condition than |ShouldAnticipateHighPriorityWork|,
+  // restricted to the case where real work is pending.
   // Must be called from the main thread.
   virtual bool ShouldYieldForHighPriorityWork() = 0;
 
   // Shuts down the scheduler by dropping any remaining pending work in the work
   // queues. After this call any work posted to the task runners will be
   // silently dropped.
   virtual void Shutdown() = 0;
 
  protected:
   RendererScheduler();
   DISALLOW_COPY_AND_ASSIGN(RendererScheduler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_H_