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 449fcd92927cd837b031cb869bfe84b213e09e2b..09200bbf78d441e8c076bbdcdd1831d2dd1c10bb 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.cc
+++ b/content/browser/renderer_host/render_widget_host_view_base.cc
@@ -111,6 +111,10 @@ 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) {