Fixes a crash when InkDropDelegate gets destroyed after its InkDropHost

ui/views/controls/button/custom_button.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_VIEWS_CONTROLS_BUTTON_CUSTOM_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_CUSTOM_BUTTON_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/events/event_constants.h"
 #include "ui/gfx/animation/animation_delegate.h"
@@ skipping 108 matching lines @@
   // holds the mouse down over the button. For this implementation,
   // we simply return IsTriggerableEvent(event).
   virtual bool ShouldEnterPushedState(const ui::Event& event);
 
   // Returns true if the button should enter hovered state; that is, if the
   // mouse is over the button, and no other window has capture (which would
   // prevent the button from receiving MouseExited events and updating its
   // state). This does not take into account enabled state.
   bool ShouldEnterHoveredState();
 
-  void SetInkDropDelegate(scoped_ptr<InkDropDelegate> ink_drop_delegate);
-  InkDropDelegate* ink_drop_delegate() const {
-    return ink_drop_delegate_.get();
+  InkDropDelegate* ink_drop_delegate() const { return ink_drop_delegate_; }
+  void set_ink_drop_delegate(InkDropDelegate* ink_drop_delegate) {
+    ink_drop_delegate_ = ink_drop_delegate;
   }
 
   // Overridden from View:
   void OnBoundsChanged(const gfx::Rect& previous_bounds) override;
   void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) override;
   void OnBlur() override;
 
   // The button state (defined in implementation)
   ButtonState state_;
@@ skipping 12 matching lines @@
 
   // Is the hover animation running because StartThrob was invoked?
   bool is_throbbing_;
 
   // Mouse event flags which can trigger button actions.
   int triggerable_event_flags_;
 
   // See description above setter.
   bool request_focus_on_press_;
 
-  // Animation delegate for the ink drop ripple effect.
-  scoped_ptr<InkDropDelegate> ink_drop_delegate_;
+  // Animation delegate for the ink drop ripple effect. It is owned by a
+  // descendant class and needs to be reset before an instance of the concrete
+  // CustomButton is destroyed.
+  InkDropDelegate* ink_drop_delegate_;
 
   // The event on which the button should notify its listener.
   NotifyAction notify_action_;
 
   DISALLOW_COPY_AND_ASSIGN(CustomButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_CUSTOM_BUTTON_H_