Fail if key synthesized events are off screen.

content/browser/renderer_host/input/synthetic_gesture_target_base.h

Index: content/browser/renderer_host/input/synthetic_gesture_target_base.h
diff --git a/content/browser/renderer_host/input/synthetic_gesture_target_base.h b/content/browser/renderer_host/input/synthetic_gesture_target_base.h
index e6697198cde112ed374ace8c85c4d07312df1c4c..8000ce2178d9e2c480f81337a362934283ffed42 100644
--- a/content/browser/renderer_host/input/synthetic_gesture_target_base.h
+++ b/content/browser/renderer_host/input/synthetic_gesture_target_base.h
@@ -56,6 +56,8 @@ class SyntheticGestureTargetBase : public SyntheticGestureTarget {
   RenderWidgetHostImpl* render_widget_host() const { return host_; }
 
  private:
+  bool PointIsWithinContents(int x, int y) const;
+
   RenderWidgetHostImpl* host_;
 
   DISALLOW_COPY_AND_ASSIGN(SyntheticGestureTargetBase);