Implement Gesture event hit testing/forwarding for OOPIF.

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 46d18138c2b13985ff0a10532d569f1b6a9c502e..ba306bb56fb79e95bd2220916043a4cd4231473f 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -362,6 +362,8 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   void ProcessMouseWheelEvent(const blink::WebMouseWheelEvent& event) override;
   void ProcessTouchEvent(const blink::WebTouchEvent& event,
                          const ui::LatencyInfo& latency) override;
+  void ProcessGestureEvent(const blink::WebGestureEvent& event,
+                           const ui::LatencyInfo& latency);
   void TransformPointToLocalCoordSpace(const gfx::Point& point,
                                        cc::SurfaceId original_surface,
                                        gfx::Point* transformed_point) override;