mac: Fix a dangling delegate bug with MCPopupController.

ui/message_center/cocoa/popup_controller.mm

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ui/message_center/cocoa/popup_controller.h"
 
 #include <cmath>
 
 #import "base/mac/foundation_util.h"
 #import "base/mac/sdk_forward_declarations.h"
@@ skipping 118 matching lines @@
                                      options:NSTrackingInVisibleRect |
                                              NSTrackingMouseEnteredAndExited |
                                              NSTrackingActiveAlways
                                        owner:self
                                     userInfo:nil]);
     [[window contentView] addTrackingArea:trackingArea_.get()];
   }
   return self;
 }
 
+#ifndef NDEBUG
+- (void)dealloc {
+  DCHECK(hasBeenClosed_);
+  [super dealloc];
+}
+#endif
+
 - (void)close {
+#ifndef NDEBUG
+  hasBeenClosed_ = YES;
+#endif
   [self setBoundsAnimation:nil];
   if (trackingArea_.get())
     [[[self window] contentView] removeTrackingArea:trackingArea_.get()];
   [super close];
   [self performSelectorOnMainThread:@selector(release)
                          withObject:nil
                       waitUntilDone:NO
                               modes:@[ NSDefaultRunLoopMode ]];
 }
 
@@ skipping 82 matching lines @@
   [self setBoundsAnimation:animation];
   [boundsAnimation_ setDuration:[popupCollection_ popupAnimationDuration]];
   [boundsAnimation_ setDelegate:self];
   [boundsAnimation_ startAnimation];
 }
 
 - (void)closeWithAnimation {
   if (isClosing_)
     return;
 
+#ifndef NDEBUG
+  hasBeenClosed_ = YES;
+#endif
   isClosing_ = YES;
 
   // If the notification was swiped closed, do not animate it as the
   // notification has already faded out.
   if (swipeGestureEnded_) {
     [self close];
     return;
   }
 
   NSDictionary* animationDict = @{
@@ skipping 33 matching lines @@
 
 - (void)mouseEntered:(NSEvent*)event {
   messageCenter_->PausePopupTimers();
 }
 
 - (void)mouseExited:(NSEvent*)event {
   messageCenter_->RestartPopupTimers();
 }
 
 @end