Notifications: Add cross-platform UMA: ShowMessageCenter, ShowSettings.

ui/message_center/views/message_center_view.cc

Index: ui/message_center/views/message_center_view.cc
diff --git a/ui/message_center/views/message_center_view.cc b/ui/message_center/views/message_center_view.cc
index 95c2cc376699f7e0f71bdf92eebc83259e1cb578..0592b4048896ca3890f66c4b590de6450cbd6ee1 100644
--- a/ui/message_center/views/message_center_view.cc
+++ b/ui/message_center/views/message_center_view.cc
@@ -934,6 +934,11 @@ void MessageCenterView::OnNotificationUpdated(const std::string& id) {
 void MessageCenterView::AnimationEnded(const ui::Animation* animation) {
   DCHECK_EQ(animation, settings_transition_animation_.get());
 
+  Visibility visibility = target_view_ == settings_view_
+                              ? VISIBILITY_SETTINGS
+                              : VISIBILITY_MESSAGE_CENTER;
+  message_center_->SetVisibility(visibility);
+
   source_view_->SetVisible(false);
   target_view_->SetVisible(true);
   if (source_view_->layer())