[ObjC ARC] Converts components/translate/ios/browser:browser to ARC.

components/translate/ios/browser/js_language_detection_manager.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 "components/translate/ios/browser/js_language_detection_manager.h"
 
 #include "base/callback.h"
-#include "base/mac/scoped_nsobject.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace language_detection {
 // Note: This should stay in sync with the constant in language_detection.js.
 const size_t kMaxIndexChars = 65535;
 }  // namespace language_detection
 
 @implementation JsLanguageDetectionManager
 
 #pragma mark - Protected methods
 
 - (NSString*)scriptPath {
@@ skipping 12 matching lines @@
   DCHECK(!callback.is_null());
   // Copy the completion handler so that the block does not capture a reference.
   __block language_detection::BufferedTextCallback blockCallback = callback;
   NSString* JS = @"__gCrWeb.languageDetection.retrieveBufferedTextContent()";
   [self executeJavaScript:JS completionHandler:^(id result, NSError*) {
     blockCallback.Run(base::SysNSStringToUTF16(result));
   }];
 }
 
 @end