Added material design mouse hover feedback support.

ui/views/controls/button/custom_button.cc

Index: ui/views/controls/button/custom_button.cc
diff --git a/ui/views/controls/button/custom_button.cc b/ui/views/controls/button/custom_button.cc
index 61b595bbfeb2f059327527ad3c1ef18e76afb270..70d090241eefe4bfe6c146c45b3b9c468b7928c7 100644
--- a/ui/views/controls/button/custom_button.cc
+++ b/ui/views/controls/button/custom_button.cc
@@ -312,6 +312,13 @@ void CustomButton::AnimationProgressed(const gfx::Animation* animation) {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// CustomButton, views::InkDropConsumer implementation:
+
+bool CustomButton::ShouldShowInkDropHover() {
+  return enabled() && IsMouseHovered();
+}
+
+////////////////////////////////////////////////////////////////////////////////
 // CustomButton, protected:
 
 CustomButton::CustomButton(ButtonListener* listener)