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

components/autofill/ios/browser/js_autofill_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/autofill/ios/browser/js_autofill_manager.h"
 
 #include "base/format_macros.h"
 #include "base/json/string_escape.h"
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @implementation JsAutofillManager
 
 - (void)fetchFormsWithMinimumRequiredFieldsCount:(NSUInteger)requiredFieldsCount
                                completionHandler:
                                    (void (^)(NSString*))completionHandler {
   DCHECK(completionHandler);
   NSString* extractFormsJS = [NSString
       stringWithFormat:@"__gCrWeb.autofill.extractForms(%" PRIuNS ");",
                        requiredFieldsCount];
   [self executeJavaScript:extractFormsJS
@@ skipping 48 matching lines @@
 }
 
 - (void)fillPredictionData:(NSString*)dataString {
   NSString* script =
       [NSString stringWithFormat:@"__gCrWeb.autofill.fillPredictionData(%@);",
                                  dataString];
   [self executeJavaScript:script completionHandler:nil];
 }
 
 @end