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

chrome/browser/renderer_host/render_widget_host_view_gtk.h

Index: chrome/browser/renderer_host/render_widget_host_view_gtk.h
diff --git a/chrome/browser/renderer_host/render_widget_host_view_gtk.h b/chrome/browser/renderer_host/render_widget_host_view_gtk.h
index 227e08117a9db0ba2debe9729f260fca115cc9fb..40824e926bc0ae7b0df7e5ec39169f04c5a6fd3a 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_gtk.h
+++ b/chrome/browser/renderer_host/render_widget_host_view_gtk.h
@@ -98,6 +98,12 @@ class RenderWidgetHostViewGtk : public RenderWidgetHostView,
   virtual void DestroyPluginContainer(gfx::PluginWindowHandle id) 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 void AcceleratedCompositingActivated(bool activated) OVERRIDE;
   virtual gfx::PluginWindowHandle GetCompositingSurface() OVERRIDE;