Use WeakNSProtocol/WeakNSObject for WebControllerObserverBridge ivars.

ios/web/web_state/web_controller_observer_bridge.h

 // Copyright 2014 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.
 
 #ifndef IOS_WEB_WEB_STATE_WEB_CONTROLLER_OBSERVER_BRIDGE_H_
 #define IOS_WEB_WEB_STATE_WEB_CONTROLLER_OBSERVER_BRIDGE_H_
 
 #include <string>
 
+#import "base/ios/weak_nsobject.h"
 #include "ios/web/public/web_state/web_state_observer.h"
 
 @class CRWWebController;
 @protocol CRWWebControllerObserver;
 class GURL;
 
 namespace base {
 class DictionaryValue;
 }
 
@@ skipping 25 matching lines @@
 
  private:
   // WebStateObserver implementation.
   void PageLoaded(PageLoadCompletionStatus load_completion_status) override;
 
   // Callback for script commands.
   bool ScriptCommandReceived(const base::DictionaryValue& value,
                              const GURL& url,
                              bool user_is_interacting);
 
-  id<CRWWebControllerObserver> web_controller_observer_;  // Weak.
-  CRWWebController* web_controller_;                      // Weak.
+  base::WeakNSProtocol<id<CRWWebControllerObserver>> web_controller_observer_;
+  base::WeakNSObject<CRWWebController> web_controller_;
   std::string script_command_callback_prefix_;
 
   DISALLOW_COPY_AND_ASSIGN(WebControllerObserverBridge);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_WEB_STATE_WEB_CONTROLLER_OBSERVER_BRIDGE_H_