Disable overscroll navigation when emulating touch.

content/browser/renderer_host/render_widget_host_delegate.h

Index: content/browser/renderer_host/render_widget_host_delegate.h
diff --git a/content/browser/renderer_host/render_widget_host_delegate.h b/content/browser/renderer_host/render_widget_host_delegate.h
index 983f2824cd8a7a53f38c73ab734a59679843fe33..91ce94316f93bb39bbdfd529c0b7a05e0a8c15d4 100644
--- a/content/browser/renderer_host/render_widget_host_delegate.h
+++ b/content/browser/renderer_host/render_widget_host_delegate.h
@@ -59,6 +59,9 @@ class CONTENT_EXPORT RenderWidgetHostDelegate {
   // 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();