Replace views::Event with ui::Event.

ui/views/controls/button/custom_button.h

Index: ui/views/controls/button/custom_button.h
===================================================================
--- ui/views/controls/button/custom_button.h	(revision 151055)
+++ ui/views/controls/button/custom_button.h	(working copy)
@@ -109,12 +109,12 @@
 
   // Returns true if the event is one that can trigger notifying the listener.
   // This implementation returns true if the left mouse button is down.
-  virtual bool IsTriggerableEvent(const Event& event);
+  virtual bool IsTriggerableEvent(const ui::Event& event);
 
   // Returns true if the button should become pressed when the user
   // holds the mouse down over the button. For this implementation,
   // we simply return IsTriggerableEvent(event).
-  virtual bool ShouldEnterPushedState(const Event& event);
+  virtual bool ShouldEnterPushedState(const ui::Event& event);
 
   // Overridden from View:
   virtual void ViewHierarchyChanged(bool is_add,