[ARC] Converts parts of ios/web/web_state to ARC.

ios/web/web_state/js/crw_js_injection_receiver.mm

 // Copyright 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 "ios/web/public/web_state/js/crw_js_injection_receiver.h"
 
 #include "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
 #import "ios/web/public/web_state/js/crw_js_injection_evaluator.h"
 #import "ios/web/public/web_state/js/crw_js_injection_manager.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @implementation CRWJSInjectionReceiver {
   // Used to evaluate JavaScripts.
-  id<CRWJSInjectionEvaluator> _evaluator;
+  __weak id<CRWJSInjectionEvaluator> _evaluator;
 
   // Map from a CRWJSInjectionManager class to its instance created for this
   // receiver.
   base::scoped_nsobject<NSMutableDictionary> _managers;
 }
 
 - (id)init {
   NOTREACHED();
   return [super init];
 }
@@ skipping 38 matching lines @@
   return manager;
 }
 
 @end
 
 @implementation CRWJSInjectionReceiver (Testing)
 - (NSDictionary*)managers {
   return _managers.get();
 }
 @end