Stop leaking Notifications when they change groupKeys.

If a Notification changes groups (either from one group to
another, or gets a group key for the first time, which takes
it out of its implicit singleton group) it should be removed
from the old group in NotificationGroupManager's mGroupMap
and re-inserted under the new one.

Unfortunately we were passing the *new* notification in the
oldNotification argument, so we would always attempt (and
fail) to remove it from the *new* group, leaving a strong
reference to the Notification inside mGroupMap under an
obsolete group key.

Bug: 26561365
Change-Id: Ie5cdceb4f843dbd363652e00fbc0f3ac6f6ef247

packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java

@@ -1914,8 +1914,9 @@ public abstract class BaseStatusBar extends SystemUI implements
         boolean shouldInterrupt = shouldInterrupt(entry, notification);
         boolean alertAgain = alertAgain(entry, n);
 
+        final StatusBarNotification oldNotification = entry.notification;
         entry.notification = notification;
-        mGroupManager.onEntryUpdated(entry, entry.notification);
+        mGroupManager.onEntryUpdated(entry, oldNotification);
 
         boolean updateSuccessful = false;
         if (applyInPlace) {