Reland of [ObjC ARC] Converts crw_web_controller to ARC.

ios/chrome/browser/installation_notifier.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 "ios/chrome/browser/installation_notifier.h"
 
 #import <UIKit/UIKit.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 114 matching lines @@
   [_notificationCenter addObserver:observer
                           selector:notificationSelector
                               name:scheme
                             object:self];
   _backoffEntry->Reset();
   if (poll)
     [self dispatchInstallationNotifierBlock];
 }
 
 - (void)unregisterForNotifications:(id)observer {
-  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  //  DCHECK_CURRENTLY_ON(web::WebThread::UI);
   NSValue* weakReferenceToObserver =
       [NSValue valueWithNonretainedObject:observer];
   [_notificationCenter removeObserver:observer];
   for (NSString* scheme in [_installedAppObservers allKeys]) {
     DCHECK([scheme isKindOfClass:[NSString class]]);
     NSMutableSet* observers = [_installedAppObservers objectForKey:scheme];
     if ([observers containsObject:weakReferenceToObserver]) {
       [observers removeObject:weakReferenceToObserver];
       if ([observers count] == 0) {
         [_installedAppObservers removeObjectForKey:scheme];
@@ skipping 70 matching lines @@
 }
 
 - (void)setSharedApplication:(id)sharedApplication {
   // Verify that the test application object responds to all the selectors that
   // will be called on it.
   CHECK([sharedApplication respondsToSelector:@selector(canOpenURL:)]);
   sharedApplication_ = (UIApplication*)sharedApplication;
 }
 
 @end