Enable ARC for //ios/web_view/internal/translate/*.m.

ios/web_view/internal/translate/web_view_translate_client.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_VIEW_INTERNAL_TRANSLATE_WEB_VIEW_TRANSLATE_CLIENT_H_
 #define IOS_WEB_VIEW_INTERNAL_TRANSLATE_WEB_VIEW_TRANSLATE_CLIENT_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 19 matching lines @@
 
 namespace ios_web_view {
 
 class WebViewTranslateClient
     : public translate::TranslateClient,
       public web::WebStateObserver,
       public web::WebStateUserData<WebViewTranslateClient> {
  public:
   // Sets the delegate passed by the embedder.
   // |delegate| is assumed to outlive this WebViewTranslateClient.
-  void set_translate_delegate(id<CWVTranslateDelegate> delegate) {
+  void set_translate_delegate(__weak id<CWVTranslateDelegate> delegate) {
     delegate_ = delegate;
   }
 
  private:
   friend class web::WebStateUserData<WebViewTranslateClient>;
 
   // The lifetime of WebViewTranslateClient is managed by WebStateUserData.
   explicit WebViewTranslateClient(web::WebState* web_state);
   ~WebViewTranslateClient() override;
 
@@ skipping 14 matching lines @@
   bool IsTranslatableURL(const GURL& url) override;
   void ShowReportLanguageDetectionErrorUI(const GURL& report_url) override;
 
   // web::WebStateObserver implementation.
   void WebStateDestroyed() override;
 
   std::unique_ptr<translate::TranslateManager> translate_manager_;
   translate::IOSTranslateDriver translate_driver_;
 
   // Delegate provided by the embedder.
-  id<CWVTranslateDelegate> delegate_;  // Weak.
+  __weak id<CWVTranslateDelegate> delegate_;

[michaeldo, 2017/03/21 16:29:18]

Please use base::WeakNSProtocol<id<CWVTranslateDelegate>> instead of __weak.
(Note that you will need to import the delegate header and remove the @protocol
from above to avoid a cryptic error.)

[Hiroshi Ichikawa, 2017/03/22 01:32:15]

Done. Just curious, what is advantage of using WeakNSProtocol instead of __weak?

[michaeldo, 2017/03/22 02:13:46]

Good question, I don't have all the details, but it certainly plays nice with
C++ and has some other guarantees like has unittests to ensure it is nil if
never set. It is modeled after scoped_nsobject which can be used to scope an
Obj-C instance even within a C++ method body. These helpers also predate ARC
adoption where a scoped obj-C obj meant you didn't need to manually release it.

 
   DISALLOW_COPY_AND_ASSIGN(WebViewTranslateClient);
 };
 
 }  // namespace ios_web_view
 
 #endif  // IOS_WEB_VIEW_INTERNAL_TRANSLATE_WEB_VIEW_TRANSLATE_CLIENT_H_