Converts parts of ios/web to ARC

ios/web/navigation/navigation_item_impl.mm

 // 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.
 
 #include "ios/web/navigation/navigation_item_impl.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <utility>
 
 #include "base/logging.h"
 #include "components/url_formatter/url_formatter.h"
 #include "ui/base/page_transition_types.h"
 #include "ui/gfx/text_elider.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 // Returns a new unique ID for use in NavigationItem during construction.  The
 // returned ID is guaranteed to be nonzero (which is the "no ID" indicator).
 static int GetUniqueIDInConstructor() {
   static int unique_id_counter = 0;
   return ++unique_id_counter;
 }
 
 }  // namespace
@@ skipping 170 matching lines @@
 
 bool NavigationItemImpl::IsOverridingUserAgent() const {
   return is_overriding_user_agent_;
 }
 
 bool NavigationItemImpl::HasPostData() const {
   return post_data_.get() != nil;
 }
 
 NSDictionary* NavigationItemImpl::GetHttpRequestHeaders() const {
-  return [[http_request_headers_ copy] autorelease];
+  return [http_request_headers_ copy];
 }
 
 void NavigationItemImpl::AddHttpRequestHeaders(
     NSDictionary* additional_headers) {
   if (!additional_headers)
     return;
 
   if (http_request_headers_)
     [http_request_headers_ addEntriesFromDictionary:additional_headers];
   else
     http_request_headers_.reset([additional_headers mutableCopy]);
 }
 
 void NavigationItemImpl::SetSerializedStateObject(
     NSString* serialized_state_object) {
-  serialized_state_object_.reset([serialized_state_object retain]);
+  serialized_state_object_.reset(serialized_state_object);

[kkhorimoto, 2016/08/19 23:15:43]

How does ARC function for C++ classes that have NSObject ivars?  Is it just
assumed that the variables use strong references?  If so, this is another place
where it'd be better to remove scoped_nsobjects.

[stkhapugin, 2016/08/22 11:37:00]

ARC treats all Cocoa object type variables in Objective-C++ files with ARC the
same. See other comment for why this is not going to be fixed now. 

 }
 
 NSString* NavigationItemImpl::GetSerializedStateObject() const {
   return serialized_state_object_.get();
 }
 
 void NavigationItemImpl::SetIsCreatedFromPushState(bool push_state) {
   is_created_from_push_state_ = push_state;
 }
 
 bool NavigationItemImpl::IsCreatedFromPushState() const {
   return is_created_from_push_state_;
 }
 
 void NavigationItemImpl::SetShouldSkipResubmitDataConfirmation(bool skip) {
   should_skip_resubmit_data_confirmation_ = skip;
 }
 
 bool NavigationItemImpl::ShouldSkipResubmitDataConfirmation() const {
   return should_skip_resubmit_data_confirmation_;
 }
 
 void NavigationItemImpl::SetPostData(NSData* post_data) {
-  post_data_.reset([post_data retain]);
+  post_data_.reset(post_data);
 }
 
 NSData* NavigationItemImpl::GetPostData() const {
   return post_data_.get();
 }
 
 void NavigationItemImpl::RemoveHttpRequestHeaderForKey(NSString* key) {
   DCHECK(key);
   [http_request_headers_ removeObjectForKey:key];
   if (![http_request_headers_ count])
     http_request_headers_.reset();
 }
 
 void NavigationItemImpl::ResetHttpRequestHeaders() {
   http_request_headers_.reset();
 }
 
 void NavigationItemImpl::ResetForCommit() {
   // Any state that only matters when a navigation item is pending should be
   // cleared here.
   set_is_renderer_initiated(false);
 }
 
 }  // namespace web