Add User Actions and adding more details to UMA metrics for overscroll navigation

content/browser/renderer_host/overscroll_controller_delegate.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_OVERSCROLL_CONTROLLER_DELEGATE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_OVERSCROLL_CONTROLLER_DELEGATE_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "content/browser/renderer_host/overscroll_controller.h"
@@ skipping 14 matching lines @@
   virtual gfx::Rect GetVisibleBounds() const = 0;
 
   // This is called for each update in the overscroll amount. Returns true if
   // the delegate consumed the event.
   virtual bool OnOverscrollUpdate(float delta_x, float delta_y) = 0;
 
   // This is called when the overscroll completes.
   virtual void OnOverscrollComplete(OverscrollMode overscroll_mode) = 0;
 
   // This is called when the direction of the overscroll changes.
+  // When a new overscroll is started (i.e. when |new_mode| is not
+  // equal to OVERSCROLL_NONE), |source| will be set to the device that
+  // triggered the overscroll gesture.
   virtual void OnOverscrollModeChange(OverscrollMode old_mode,
-                                      OverscrollMode new_mode) = 0;
+                                      OverscrollMode new_mode,
+                                      OverscrollSource source) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(OverscrollControllerDelegate);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_OVERSCROLL_CONTROLLER_DELEGATE_H_