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

chrome/browser/renderer_host/render_widget_host_view_gtk.cc

Index: chrome/browser/renderer_host/render_widget_host_view_gtk.cc
diff --git a/chrome/browser/renderer_host/render_widget_host_view_gtk.cc b/chrome/browser/renderer_host/render_widget_host_view_gtk.cc
index e3b1e13ad62600d6d41e510bbb8e7ded3306882c..8f46c9f538ef2d768ddaa4811151e437ccb545cb 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_gtk.cc
+++ b/chrome/browser/renderer_host/render_widget_host_view_gtk.cc
@@ -1119,6 +1119,19 @@ void RenderWidgetHostViewGtk::SetVisuallyDeemphasized(
   }
 }
 
+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());