Don't restart the hang renderer timeout on messages ack'd from the compositor thread.

content/browser/renderer_host/render_widget_host_impl.h

 // Copyright (c) 2012 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_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 603 matching lines @@
   // Give key press listeners a chance to handle this key press. This allow
   // widgets that don't have focus to still handle key presses.
   bool KeyPressListenersHandleEvent(const NativeWebKeyboardEvent& event);
 
   // InputRouterClient
   InputEventAckState FilterInputEvent(
       const blink::WebInputEvent& event,
       const ui::LatencyInfo& latency_info) override;
   void IncrementInFlightEventCount(
       blink::WebInputEvent::Type event_type) override;
-  void DecrementInFlightEventCount() override;
+  void DecrementInFlightEventCount(InputEventAckSource ack_source) override;
   void OnHasTouchEventHandlers(bool has_handlers) override;
   void DidFlush() override;
   void DidOverscroll(const ui::DidOverscrollParams& params) override;
   void DidStopFlinging() override;
 
   // Dispatch input events with latency information
   void DispatchInputEventWithLatencyInfo(const blink::WebInputEvent& event,
                                          ui::LatencyInfo* latency);
 
   // InputAckHandler
@@ skipping 220 matching lines @@
 #endif
 
   base::WeakPtrFactory<RenderWidgetHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_