Mac: Fix lifetime problem under BookmarkBarController stopPulsingBookmarkNode.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm

 // Copyright (c) 2012 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 "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.h"
 
 #include <stddef.h>
 
 #import "base/mac/bundle_locations.h"
 #import "base/mac/foundation_util.h"
@@ skipping 343 matching lines @@
 
     node = node->parent();
   }
   NOTREACHED();
   return nil;
 }
 
 - (void)startPulsingBookmarkNode:(const BookmarkNode*)node {
   [self stopPulsingBookmarkNode];
 
-  pulsingButton_ = [self bookmarkButtonToPulseForNode:node];
+  pulsingButton_.reset([self bookmarkButtonToPulseForNode:node],
+                       base::scoped_policy::RETAIN);
   if (!pulsingButton_)
     return;
 
   [pulsingButton_ setPulseIsStuckOn:YES];
   pulsingBookmarkObserver_.reset(
       new BookmarkModelObserverForCocoa(bookmarkModel_, ^() {
         // Stop pulsing if anything happened to the node.
         [self stopPulsingBookmarkNode];
       }));
   pulsingBookmarkObserver_->StartObservingNode(node);
 }
 
 - (void)stopPulsingBookmarkNode {
   if (!pulsingButton_)
     return;
 
   [pulsingButton_ setPulseIsStuckOn:NO];
-  pulsingButton_ = nil;
+  pulsingButton_.reset();
   pulsingBookmarkObserver_.reset();
 }
 
 - (void)dealloc {
   [self browserWillBeDestroyed];
   [super dealloc];
 }
 
 - (void)browserWillBeDestroyed {
   // If |bridge_| is null it means -viewDidLoad has not yet been called, which
@@ skipping 2612 matching lines @@
 - (id<BookmarkButtonControllerProtocol>)controllerForNode:
     (const BookmarkNode*)node {
   // See if it's in the bar, then if it is in the hierarchy of visible
   // folder menus.
   if (bookmarkModel_->bookmark_bar_node() == node)
     return self;
   return [folderController_ controllerForNode:node];
 }
 
 @end