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

content/browser/renderer_host/input/input_router_client.h

Index: content/browser/renderer_host/input/input_router_client.h
diff --git a/content/browser/renderer_host/input/input_router_client.h b/content/browser/renderer_host/input/input_router_client.h
index b22290d3d90d1626030002a47514b8381d2fafaa..3c45aa88ad450de175e233378568c6bd75cd625a 100644
--- a/content/browser/renderer_host/input/input_router_client.h
+++ b/content/browser/renderer_host/input/input_router_client.h
@@ -7,6 +7,7 @@
 
 #include "content/browser/renderer_host/event_with_latency_info.h"
 #include "content/common/content_export.h"
+#include "content/common/input/input_event_ack_source.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "content/public/browser/native_web_keyboard_event.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
@@ -36,7 +37,7 @@ class CONTENT_EXPORT InputRouterClient {
   virtual void IncrementInFlightEventCount(blink::WebInputEvent::Type type) = 0;
 
   // Called each time a WebInputEvent ACK IPC is received.
-  virtual void DecrementInFlightEventCount() = 0;
+  virtual void DecrementInFlightEventCount(InputEventAckSource ack_source) = 0;
 
   // Called when the renderer notifies that it has touch event handlers.
   virtual void OnHasTouchEventHandlers(bool has_handlers) = 0;