Pause close timer of notification while it's active

ui/message_center/views/toast_contents_view.h

Index: ui/message_center/views/toast_contents_view.h
diff --git a/ui/message_center/views/toast_contents_view.h b/ui/message_center/views/toast_contents_view.h
index 77a4def3513bab2c10ff7bf6c8378d7c1519ba4d..1161a0b05344271936c9506ec3f279fec029a6d2 100644
--- a/ui/message_center/views/toast_contents_view.h
+++ b/ui/message_center/views/toast_contents_view.h
@@ -15,6 +15,7 @@
 #include "ui/message_center/message_center_export.h"
 #include "ui/message_center/views/message_center_controller.h"
 #include "ui/views/widget/widget_delegate.h"
+#include "ui/views/widget/widget_observer.h"
 
 namespace gfx {
 class Animation;
@@ -42,6 +43,7 @@ class PopupAlignmentDelegate;
 // widget/views are closed/destructed.
 class MESSAGE_CENTER_EXPORT ToastContentsView
     : public views::WidgetDelegateView,
+      public views::WidgetObserver,
       public MessageCenterController,
       public gfx::AnimationDelegate {
  public:
@@ -117,6 +119,9 @@ class MESSAGE_CENTER_EXPORT ToastContentsView
   void OnDisplayChanged() override;
   void OnWorkAreaChanged() override;
 
+  // Overridden from views::WidgetObserver:
+  void OnWidgetActivationChanged(views::Widget* widget, bool active) override;
+
   // Recalculates preferred size from underlying view and notifies about it.
   void UpdatePreferredSize();