re-land the "SourceEventType added to LatencyInfo."

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 298 matching lines @@
   // a page load. This stops |new_content_rendering_timeout_|, or prevents
   // the timer from running if the load commit message hasn't been received
   // yet.
   void OnFirstPaintAfterLoad();
 
   // Forwards the given message to the renderer. These are called by the view
   // when it has received a message.
   void ForwardGestureEventWithLatencyInfo(
       const blink::WebGestureEvent& gesture_event,
       const ui::LatencyInfo& ui_latency) override;
-  void ForwardTouchEventWithLatencyInfo(
+  virtual void ForwardTouchEventWithLatencyInfo(
       const blink::WebTouchEvent& touch_event,
-      const ui::LatencyInfo& ui_latency);
+      const ui::LatencyInfo& ui_latency);  // Virtual for testing.
   void ForwardMouseEventWithLatencyInfo(
       const blink::WebMouseEvent& mouse_event,
       const ui::LatencyInfo& ui_latency);
   virtual void ForwardWheelEventWithLatencyInfo(
       const blink::WebMouseWheelEvent& wheel_event,
       const ui::LatencyInfo& ui_latency); // Virtual for testing.
 
   // Enables/disables touch emulation using mouse event. See TouchEmulator.
   void SetTouchEventEmulationEnabled(
       bool enabled, ui::GestureProviderConfigType config_type);
@@ skipping 514 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_