Fix for crbug.com/111185.

content/browser/renderer_host/render_widget_host.h

Index: content/browser/renderer_host/render_widget_host.h
diff --git a/content/browser/renderer_host/render_widget_host.h b/content/browser/renderer_host/render_widget_host.h
index 43c19059a37ce4fefa4d7069870c895a51134678..ff63189a6a0679d19c8e866398e3e23c94c99264 100644
--- a/content/browser/renderer_host/render_widget_host.h
+++ b/content/browser/renderer_host/render_widget_host.h
@@ -533,6 +533,9 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Channel::Listener,
   // initialization.
   bool renderer_initialized_;
 
+  // This value indicates how long to wait before we consider a renderer hung.
+  int hung_renderer_delay_ms_;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostTest, Resize);
   FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostTest, ResizeThenCrash);
@@ -636,6 +639,14 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Channel::Listener,
   // input messages to be coalesced.
   void ProcessWheelAck(bool processed);
 
+  // These two methods are being used by the "hung renderer" monitoring
+  // mechanism. This mechanism relies on starting a timer and counting
+  // input events going to the renderer as well as the corresponding
+  // acks coming back from the renderer. The two methods below are used
+  // for counting.
+  void RecordInputEvent();
+  bool RecordInputEventAck();
+
   // True if renderer accessibility is enabled. This should only be set when a
   // screenreader is detected as it can potentially slow down Chrome.
   bool renderer_accessible_;
@@ -743,6 +754,10 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Channel::Listener,
   // the renderer hung if it does not generate an appropriate response message.
   base::Time time_when_considered_hung_;
 
+  // This value denotes the number of input events yet to be acknowledged
+  // by the renderer.
+  int event_count_;
+
   // This timer runs to check if time_when_considered_hung_ has past.
   base::OneShotTimer<RenderWidgetHost> hung_renderer_timer_;