Make mouse wheel events trigger WebContentsObserver::DidGetUserInteraction.

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 <list>
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/process/kill.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
-#include "base/timer/timer.h"
+#include "base/timer/elapsed_timer.h"
 #include "build/build_config.h"
 #include "cc/resources/shared_bitmap.h"
 #include "content/browser/renderer_host/event_with_latency_info.h"
 #include "content/browser/renderer_host/input/input_ack_handler.h"
 #include "content/browser/renderer_host/input/input_router_client.h"
 #include "content/browser/renderer_host/input/render_widget_host_latency_tracker.h"
 #include "content/browser/renderer_host/input/synthetic_gesture.h"
 #include "content/browser/renderer_host/input/touch_emulator_client.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/input/input_event_ack_state.h"
@@ skipping 814 matching lines @@
   // causing HasFocus to return false when is_focused_ is true.
   bool is_focused_;
 
   // This value indicates how long to wait before we consider a renderer hung.
   base::TimeDelta hung_renderer_delay_;
 
   // This value indicates how long to wait for a new compositor frame from a
   // renderer process before clearing any previously displayed content.
   base::TimeDelta new_content_rendering_delay_;
 
+  // Timer used to batch together mouse wheel events for the delegate
+  // OnUserInteraction method. A wheel event is only dispatched when a wheel
+  // event has not been seen for kMouseWheelCoalesceInterval seconds prior.
+  scoped_ptr<base::ElapsedTimer> mouse_wheel_coalesce_timer_;
+
   base::WeakPtrFactory<RenderWidgetHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_