mac: Only let two-finger-scrolling trigger history if web doesn't swallow gesture

chrome/browser/renderer_host/render_widget_host_view_win.h

 // Copyright (c) 2011 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 CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_WIN_H_
 #define CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_WIN_H_
 #pragma once
 
 #include <atlbase.h>
 #include <atlapp.h>
@@ skipping 148 matching lines @@
   virtual void RenderViewGone(base::TerminationStatus status,
                               int error_code) OVERRIDE;
   // called by TabContents before DestroyWindow
   virtual void WillWmDestroy() OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual void SetTooltipText(const std::wstring& tooltip_text) OVERRIDE;
   virtual BackingStore* AllocBackingStore(const gfx::Size& size) OVERRIDE;
   virtual void SetBackground(const SkBitmap& background) OVERRIDE;
   virtual void SetVisuallyDeemphasized(const SkColor* color,
                                        bool animate) OVERRIDE;
+  virtual void UnhandledWheelEvent(
+      const WebKit::WebMouseWheelEvent& event) OVERRIDE;
+  virtual void SetHasHorizontalScrollbar(
+      bool has_horizontal_scrollbar) OVERRIDE;
+  virtual void SetScrollOffsetPinning(
+      bool is_pinned_to_left, bool is_pinned_to_right) OVERRIDE;
   virtual gfx::PluginWindowHandle GetCompositingSurface() OVERRIDE;
   virtual void ShowCompositorHostWindow(bool show) OVERRIDE;
   virtual void OnAccessibilityNotifications(
       const std::vector<ViewHostMsg_AccessibilityNotification_Params>& params
       ) OVERRIDE;
 
   // Implementation of NotificationObserver:
   virtual void Observe(int type,
                        const NotificationSource& source,
                        const NotificationDetails& details) OVERRIDE;
@@ skipping 192 matching lines @@
 
   ScopedVector<ui::ViewProp> props_;
 
   // Is the widget fullscreen?
   bool is_fullscreen_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewWin);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_WIN_H_