[ObjC ARC] Converts ios/public/provider/chrome/browser:test_support to ARC.

ios/public/provider/chrome/browser/test_chrome_browser_provider.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.
 
 #include "ios/public/provider/chrome/browser/test_chrome_browser_provider.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
-#include "base/mac/scoped_nsobject.h"
 #include "base/memory/ptr_util.h"
 #include "ios/public/provider/chrome/browser/distribution/test_app_distribution_provider.h"
 #include "ios/public/provider/chrome/browser/images/test_branded_image_provider.h"
 #include "ios/public/provider/chrome/browser/omaha/test_omaha_service_provider.h"
 #include "ios/public/provider/chrome/browser/signin/fake_chrome_identity_service.h"
 #include "ios/public/provider/chrome/browser/signin/test_signin_resources_provider.h"
 #import "ios/public/provider/chrome/browser/spotlight/test_spotlight_provider.h"
 #import "ios/public/provider/chrome/browser/ui/test_styled_text_field.h"
 #import "ios/public/provider/chrome/browser/user_feedback/test_user_feedback_provider.h"
 #import "ios/public/provider/chrome/browser/voice/test_voice_search_provider.h"
 #import "ios/public/provider/chrome/browser/voice/voice_search_language.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace ios {
 
 TestChromeBrowserProvider::TestChromeBrowserProvider()
     : app_distribution_provider_(
           base::MakeUnique<TestAppDistributionProvider>()),
       branded_image_provider_(base::MakeUnique<TestBrandedImageProvider>()),
       omaha_service_provider_(base::MakeUnique<TestOmahaServiceProvider>()),
       signin_resources_provider_(
           base::MakeUnique<TestSigninResourcesProvider>()),
       voice_search_provider_(base::MakeUnique<TestVoiceSearchProvider>()),
@@ skipping 19 matching lines @@
   chrome_identity_service_.swap(service);
 }
 
 ChromeIdentityService* TestChromeBrowserProvider::GetChromeIdentityService() {
   if (!chrome_identity_service_) {
     chrome_identity_service_.reset(new FakeChromeIdentityService());
   }
   return chrome_identity_service_.get();
 }
 
 UITextField<TextFieldStyling>* TestChromeBrowserProvider::CreateStyledTextField(

[rohitrao (ping after 24h), 2017/05/30 15:10:16]

@stk how does ARC handle a C++ method that returns an ObjC object?  Do we need
to do anything special here with annotations?

[stkhapugin, 2017/05/30 15:29:19]

In this case, the returned object must have a retain count of +1 to match the
pre-ARC implementation. To achieve this, NS_RETURNS_RETAINED annotation is
necessary. However, it is already in place in the header:

  UITextField<TextFieldStyling>* CreateStyledTextField(
      CGRect frame) const override NS_RETURNS_RETAINED;

Thus no need to add anything. 

     CGRect frame) const {
   return [[TestStyledTextField alloc] initWithFrame:frame];
 }
 
 VoiceSearchProvider* TestChromeBrowserProvider::GetVoiceSearchProvider() const {
   return voice_search_provider_.get();
 }
 
 AppDistributionProvider* TestChromeBrowserProvider::GetAppDistributionProvider()
     const {
@@ skipping 18 matching lines @@
     const {
   return branded_image_provider_.get();
 }
 
 id<NativeAppWhitelistManager>
 TestChromeBrowserProvider::GetNativeAppWhitelistManager() const {
   return nil;
 }
 
 }  // namespace ios