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

ios/web/web_state/js/crw_js_injection_manager.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_manager.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "base/mac/bundle_locations.h"
 #import "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/web/public/web_state/js/crw_js_injection_receiver.h"
 #import "ios/web/web_state/js/page_script_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @implementation CRWJSInjectionManager {
   // JS to inject into the page. This may be nil if it has been purged due to
   // low memory.
   base::scoped_nsobject<NSString> _injectObject;
   // An object the can receive JavaScript injection.
-  CRWJSInjectionReceiver* _receiver;  // Weak.
+  __weak CRWJSInjectionReceiver* _receiver;
 }
 
 - (id)initWithReceiver:(CRWJSInjectionReceiver*)receiver {
   DCHECK(receiver);
   self = [super init];
   if (self) {
     _receiver = receiver;
     // Register for low-memory warnings.
     [[NSNotificationCenter defaultCenter]
         addObserver:self
            selector:@selector(lowMemoryWarning:)
                name:UIApplicationDidReceiveMemoryWarningNotification
              object:nil];
   }
   return self;
 }
 
 - (void)dealloc {
   [[NSNotificationCenter defaultCenter] removeObserver:self];
-  [super dealloc];
 }
 
 - (BOOL)hasBeenInjected {
   return [_receiver scriptHasBeenInjectedForClass:[self class]];
 }
 
 - (void)inject {
   if ([self hasBeenInjected])
     return;
   [_receiver injectScript:[self injectionContent] forClass:[self class]];
@@ skipping 25 matching lines @@
   if (!_injectObject)
     _injectObject.reset([[self staticInjectionContent] copy]);
   return _injectObject.get();
 }
 
 - (NSString*)staticInjectionContent {
   return web::GetPageScript([self scriptPath]);
 }
 
 @end