Adds OnClickCanceled callback to views::Button

ui/views/controls/button/button.h

Index: ui/views/controls/button/button.h
diff --git a/ui/views/controls/button/button.h b/ui/views/controls/button/button.h
index 84ca047b145c2fb26d65db01a8473cc36098de28..3957597e6d4a4d85d2382b9b7488fa7017ba874a 100644
--- a/ui/views/controls/button/button.h
+++ b/ui/views/controls/button/button.h
@@ -69,6 +69,9 @@ class VIEWS_EXPORT Button : public View {
   // Cause the button to notify the listener that a click occurred.
   virtual void NotifyClick(const ui::Event& event);
 
+  // Called when a button gets released without triggering an action.

[bruthig, 2015/10/22 15:18:50]

I think you should be explicit here about this only being called for mouse
releases and not gestures.  Either in the documentation of the method name.

Consider:

// Called when a button gets released without triggering an action.
// Note: This is only wired up for button releases caused by mouse
// button releases AND not gesture events.
virtual void NotifyMouseReleasedWithoutClick(const ui::Event& event);

[varkha, 2015/10/23 15:49:46]

Done.

+  virtual void NotifyReleasedWithoutClick(const ui::Event& event);
+
   // The button's listener. Notified when clicked.
   ButtonListener* listener_;