Add UMA/Telemetry stats for end-to-end scroll latency

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 <deque>
 #include <list>
 #include <map>
@@ skipping 519 matching lines @@
                          int event_size, const ui::LatencyInfo& latency_info,
                          bool is_keyboard_shortcut);
 
   // Internal forwarding implementations that take a LatencyInfo.
   virtual void ForwardMouseEventWithLatencyInfo(
       const MouseEventWithLatencyInfo& mouse_event);
   virtual void ForwardWheelEventWithLatencyInfo(
       const WebKit::WebMouseWheelEvent& wheel_event,
       const ui::LatencyInfo& latency_info);
 
-  // Create a LatencyInfo struct for a new input event that was just received.
-  ui::LatencyInfo NewInputLatencyInfo();
+  // Create a LatencyInfo struct with INPUT_EVENT_LATENCY_RWH_COMPONENT
+  // component. If |original| is not NULL, it is merged into the resulting
+  // LatencyInfo.
+  ui::LatencyInfo NewInputLatencyInfo(const ui::LatencyInfo* original);
 
   // Called when we receive a notification indicating that the renderer
   // process has gone. This will reset our state so that our state will be
   // consistent if a new renderer is created.
   void RendererExited(base::TerminationStatus status, int exit_code);
 
   // Retrieves an id the renderer can use to refer to its view.
   // This is used for various IPC messages, including plugins.
   gfx::NativeViewId GetNativeViewId() const;
 
@@ skipping 398 matching lines @@
   int64 last_input_number_;
 
   BrowserRenderingStats rendering_stats_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_