Fix Mac App Launcher observer lifetime on AppListItemList

chrome/browser/ui/app_list/app_list_service_mac.mm

 // Copyright 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 "chrome/browser/ui/app_list/app_list_service_mac.h"
 
 #include <ApplicationServices/ApplicationServices.h>
 #import <Cocoa/Cocoa.h>
 
 #include "base/bind.h"
@@ skipping 374 matching lines @@
 
 void AppListServiceMac::CreateForProfile(Profile* requested_profile) {
   if (profile_ == requested_profile)
     return;
 
   profile_ = requested_profile;
 
   if (!window_controller_)
     window_controller_.reset([[AppListWindowController alloc] init]);
 
+  [[window_controller_ appListViewController] setDelegate:nil];
   [[window_controller_ appListViewController]
       setDelegate:GetViewDelegate(profile_)];
 }
 
 void AppListServiceMac::ShowForProfile(Profile* requested_profile) {
   InvalidatePendingProfileLoads();
 
   if (requested_profile == profile_) {
     ShowWindowNearDock();
     return;
@@ skipping 197 matching lines @@
 
 - (void)animationDidEnd:(NSAnimation*)animation {
   content::BrowserThread::PostTask(
       content::BrowserThread::UI,
       FROM_HERE,
       base::Bind(&AppListServiceMac::WindowAnimationDidEnd,
                  base::Unretained(AppListServiceMac::GetInstance())));
 }
 
 @end