Introduce bottom controls to CC and let it respond to scrolling

content/browser/renderer_host/render_widget_host_view_base.cc

Index: content/browser/renderer_host/render_widget_host_view_base.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_base.cc b/content/browser/renderer_host/render_widget_host_view_base.cc
index 41724ead586ebe5c9461dbe00f581442d29d6601..0338787ca1377bd246aece7b0e78313e6d542a72 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.cc
+++ b/content/browser/renderer_host/render_widget_host_view_base.cc
@@ -108,6 +108,10 @@ void RenderWidgetHostViewBase::SelectionBoundsChanged(
     GetTextInputManager()->SelectionBoundsChanged(this, params);
 }
 
+float RenderWidgetHostViewBase::GetBottomControlsHeight() const {
+  return 0.f;
+}
+
 void RenderWidgetHostViewBase::SelectionChanged(const base::string16& text,
                                                 size_t offset,
                                                 const gfx::Range& range) {