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

content/renderer/input/input_event_filter.cc

Index: content/renderer/input/input_event_filter.cc
diff --git a/content/renderer/input/input_event_filter.cc b/content/renderer/input/input_event_filter.cc
index 56799b1128b224d40efe5c5edff70d23b09efa44..5e68b53ad1d49bac8994895b130c5682998d775b 100644
--- a/content/renderer/input/input_event_filter.cc
+++ b/content/renderer/input/input_event_filter.cc
@@ -264,8 +264,10 @@ void InputEventFilter::DidForwardToHandlerAndOverscroll(
   if (!send_ack)
     return;
 
-  InputEventAck ack(type, ack_state, latency_info, std::move(overscroll_params),
-                    unique_touch_event_id);
+  InputEventAck ack(
+      InputEventAckLocation::INPUT_EVENT_ACK_LOCATION_COMPOSITOR_THREAD, type,
+      ack_state, latency_info, std::move(overscroll_params),
+      unique_touch_event_id);
   SendMessage(std::unique_ptr<IPC::Message>(
       new InputHostMsg_HandleInputEvent_ACK(routing_id, ack)));
 }
@@ -302,7 +304,9 @@ void InputEventFilter::SendInputEventAck(int routing_id,
                                          blink::WebInputEvent::Type type,
                                          InputEventAckState ack_result,
                                          uint32_t touch_event_id) {
-  InputEventAck ack(type, ack_result, touch_event_id);
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  InputEventAck ack(InputEventAckLocation::INPUT_EVENT_ACK_LOCATION_MAIN_THREAD,
+                    type, ack_result, touch_event_id);
   SendMessage(std::unique_ptr<IPC::Message>(
       new InputHostMsg_HandleInputEvent_ACK(routing_id, ack)));
 }