Handle mac trackpad zoom via GesturePinch events

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index e6135d1db216fd96784603ac9e28d62291bd11da..437d0b5e93d8b5d9ada052276e1dcc83cc7e1338 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -486,6 +486,8 @@ class CONTENT_EXPORT WebContentsImpl
       const blink::WebMouseWheelEvent& event) OVERRIDE;
   virtual bool PreHandleGestureEvent(
       const blink::WebGestureEvent& event) OVERRIDE;
+  virtual bool HandleGestureEvent(
+      const blink::WebGestureEvent& event) OVERRIDE;
   virtual void DidSendScreenRects(RenderWidgetHostImpl* rwh) OVERRIDE;
 #if defined(OS_WIN)
   virtual gfx::NativeViewAccessible GetParentNativeViewAccessible() OVERRIDE;
@@ -984,6 +986,11 @@ class CONTENT_EXPORT WebContentsImpl
   // remember it.
   bool temporary_zoom_settings_;
 
+  // The raw accumulated zoom value and the actual zoom increments made for an
+  // an in-progress pinch gesture.
+  float totalPinchGestureAmount_;
+  int currentPinchZoomStepDelta_;
+
   // The intrinsic size of the page.
   gfx::Size preferred_size_;