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

content/renderer/input/render_widget_input_handler.cc

 // Copyright 2015 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.
 
 #include "content/renderer/input/render_widget_input_handler.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
@@ skipping 387 matching lines @@
 
   if (dispatch_type == DISPATCH_TYPE_BLOCKING_NOTIFY_MAIN) {
     // |non_blocking| means it was ack'd already by the InputHandlerProxy
     // so let the delegate know the event has been handled.
     delegate_->NotifyInputEventHandled(input_event.type, ack_result);
   }
 
   if ((dispatch_type == DISPATCH_TYPE_BLOCKING ||
        dispatch_type == DISPATCH_TYPE_BLOCKING_NOTIFY_MAIN)) {
     std::unique_ptr<InputEventAck> response(new InputEventAck(
-        input_event.type, ack_result, swap_latency_info,
-        std::move(event_overscroll),
+        InputEventAckSource::MAIN_THREAD, input_event.type, ack_result,
+        swap_latency_info, std::move(event_overscroll),
         ui::WebInputEventTraits::GetUniqueTouchEventId(input_event)));
     delegate_->OnInputEventAck(std::move(response));
   } else {
     DCHECK(!event_overscroll) << "Unexpected overscroll for un-acked event";
   }
   if (RenderThreadImpl::current()) {
     RenderThreadImpl::current()
         ->GetRendererScheduler()
         ->DidHandleInputEventOnMainThread(input_event);
   }
@@ skipping 49 matching lines @@
   // it can be bundled in the event ack.
   if (handling_event_overscroll_) {
     *handling_event_overscroll_ = std::move(params);
     return;
   }
 
   delegate_->OnDidOverscroll(*params);
 }
 
 }  // namespace content