Add VectorIconButton functionality to ImageButton.

ui/views/views_delegate.cc

Index: ui/views/views_delegate.cc
diff --git a/ui/views/views_delegate.cc b/ui/views/views_delegate.cc
index a14cf4882998ba300f4f8e1d42605e57716af110..94d6fe1431923b8d611e79dae4b636be886ad857 100644
--- a/ui/views/views_delegate.cc
+++ b/ui/views/views_delegate.cc
@@ -160,6 +160,10 @@ int ViewsDelegate::GetDistanceMetric(DistanceMetric metric) const {
   return 0;
 }
 
+gfx::Insets ViewsDelegate::GetButtonMargins() const {
+  return gfx::Insets(kButtonExtraTouchSize);
+}
+
 ViewsDelegate::ViewsDelegate()
     : views_tsc_factory_(new ViewsTouchEditingControllerFactory) {
   DCHECK(!views_delegate);