mac: History swiping doesn't work right with iframes.

content/port/browser/render_widget_host_view_port.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_
 #define CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 270 matching lines @@
   // the GestureRecognizer until invocation of ProcessAckedTouchEvent releases
   // it to be consumed (when |ack_result| is NOT_CONSUMED OR NO_CONSUMER_EXISTS)
   // or ignored (when |ack_result| is CONSUMED).
   virtual void ProcessAckedTouchEvent(const TouchEventWithLatencyInfo& touch,
                                       InputEventAckState ack_result) = 0;
 
   virtual void SetHasHorizontalScrollbar(bool has_horizontal_scrollbar) = 0;
   virtual void SetScrollOffsetPinning(
       bool is_pinned_to_left, bool is_pinned_to_right) = 0;
 
-  // Called when a mousewheel event was not processed by the renderer.
-  virtual void UnhandledWheelEvent(const blink::WebMouseWheelEvent& event) = 0;
+  // When a wheel event is first received, it is sent to the renderer.  This
+  // method is invoked once the renderer, and |delegate_| have been given a
+  // chance to process the wheel event. |consumed| indicates whether either
+  // chose to process the |event|. At most one entity should consume an event.
+  virtual void HandledWheelEvent(const blink::WebMouseWheelEvent& event,
+                                 bool consumed) = 0;
 
   // Called prior to forwarding input event messages to the renderer, giving
   // the view a chance to perform in-process event filtering or processing.
   // Return values of |NOT_CONSUMED| or |UNKNOWN| will result in |input_event|
   // being forwarded.
   virtual InputEventAckState FilterInputEvent(
       const blink::WebInputEvent& input_event) = 0;
 
   // Called by the host when it requires an input flush; the flush call should
   // by synchronized with BeginFrame.
@@ skipping 54 matching lines @@
 
   // Returns an HWND that's given as the parent window for windowless Flash to
   // workaround crbug.com/301548.
   virtual gfx::NativeViewId GetParentForWindowlessPlugin() const = 0;
 #endif
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_