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

chrome/browser/renderer_host/render_widget_host_view_gtk.cc

 // 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.
 
 #include "chrome/browser/renderer_host/render_widget_host_view_gtk.h"
 
 // If this gets included after the gtk headers, then a bunch of compiler
 // errors happen because of a "#define Status int" in Xlib.h, which interacts
 // badly with net::URLRequestStatus::Status.
 #include "chrome/common/render_messages.h"
@@ skipping 1101 matching lines @@
 
   if (animate) {
     overlay_animation_.Reset();
     overlay_animation_.Show();
   } else {
     overlay_animation_.Reset(1.0);
     gtk_widget_queue_draw(view_.get());
   }
 }
 
+void RenderWidgetHostViewGtk::UnhandledWheelEvent(
+    const WebKit::WebMouseWheelEvent& event) {
+}
+
+void RenderWidgetHostViewGtk::SetHasHorizontalScrollbar(
+    bool has_horizontal_scrollbar) {
+}
+
+void RenderWidgetHostViewGtk::SetScrollOffsetPinning(
+    bool is_pinned_to_left, bool is_pinned_to_right) {
+}
+
+
 void RenderWidgetHostViewGtk::AcceleratedCompositingActivated(bool activated) {
   GtkPreserveWindow* widget =
     reinterpret_cast<GtkPreserveWindow*>(view_.get());
 
   gtk_preserve_window_delegate_resize(widget, activated);
 }
 
 gfx::PluginWindowHandle RenderWidgetHostViewGtk::GetCompositingSurface() {
   if (compositing_surface_ == gfx::kNullPluginWindow) {
     GtkNativeViewManager* manager = GtkNativeViewManager::GetInstance();
@@ skipping 55 matching lines @@
 }
 
 // static
 RenderWidgetHostView*
     RenderWidgetHostView::GetRenderWidgetHostViewFromNativeView(
         gfx::NativeView widget) {
   gpointer user_data = g_object_get_data(G_OBJECT(widget),
                                          kRenderWidgetHostViewKey);
   return reinterpret_cast<RenderWidgetHostView*>(user_data);
 }