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..648174f8a725ec238a6f7b61da21a77b995a0112 100644
--- a/ui/views/controls/button/button.h
+++ b/ui/views/controls/button/button.h
@@ -69,6 +69,12 @@ 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 or when
+  // a NOTIFY_ON_PRESS button is pressed with a wrong mouse button.
+  // Note: This is only wired up for mouse button events AND not gesture
+  // events.

[sadrul, 2015/11/25 22:18:42]

*and

[varkha, 2015/11/25 22:35:48]

Done.

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