Disable overscroll navigation when emulating touch.

content/browser/renderer_host/render_widget_host_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_RENDER_WIDGET_HOST_DELEGATE_H_
 #define CONTENT_BROWSER_RENDER_WIDGET_HOST_DELEGATE_H_
 
 #include "build/build_config.h"
 #include "content/common/content_export.h"
 #include "ui/gfx/native_widget_types.h"
@@ skipping 41 matching lines @@
   // Returns true if the |event| was handled.
   virtual bool PreHandleGestureEvent(const blink::WebGestureEvent& event);
 
   // Callback to inform the browser that the renderer did not process the
   // specified gesture event.  Returns true if the |event| was handled.
   virtual bool HandleGestureEvent(const blink::WebGestureEvent& event);
 
   // Notifies that screen rects were sent to renderer process.
   virtual void DidSendScreenRects(RenderWidgetHostImpl* rwh) {}
 
+  // Notifies that RenderWidgetHost will toggle touch emulation.
+  virtual void OnTouchEmulationEnabled(bool enabled) {}
+
 #if defined(OS_WIN)
   // Returns the widget's parent's NativeViewAccessible.
   virtual gfx::NativeViewAccessible GetParentNativeViewAccessible();
 #endif
 
  protected:
   virtual ~RenderWidgetHostDelegate() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDER_WIDGET_HOST_DELEGATE_H_