Fix page navigation being incorrectly fired on Mac OSX.

content/browser/renderer_host/render_widget_host_view_mac.h

Index: content/browser/renderer_host/render_widget_host_view_mac.h
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index 48d00f747fbb69a42b872db92d878d761b11efce..2a4ad7fc80c7b6196f9931b1cbf8f3c1aa025ec9 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -348,6 +348,8 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   void UnlockMouse() override;
   void WheelEventAck(const blink::WebMouseWheelEvent& event,
                      InputEventAckState ack_result) override;
+  void GestureEventAck(const blink::WebGestureEvent& event,
+                       InputEventAckState ack_result) override;
 
   scoped_ptr<SyntheticGestureTarget> CreateSyntheticGestureTarget() override;
 
@@ -588,6 +590,9 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   // RenderWidgetHostViewGuest.
   bool is_guest_view_hack_;
 
+  // True if gestures are generated for mouse wheel events.
+  bool wheel_gestures_enabled_;
+
   // selected text on the renderer.
   std::string selected_text_;