Introduce FakeChromeIdentity and FakeChromeIdentityService.

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"
 
 #include "base/logging.h"
-#include "ios/public/provider/chrome/browser/signin/chrome_identity_service.h"
+#include "ios/public/provider/chrome/browser/signin/fake_chrome_identity_service.h"
 #import "ios/public/provider/chrome/browser/test_updatable_resource_provider.h"
 
 namespace ios {
 
 TestChromeBrowserProvider::TestChromeBrowserProvider()
-    : chrome_identity_service_(new ios::ChromeIdentityService),
+    : chrome_identity_service_(new ios::FakeChromeIdentityService),
       test_updatable_resource_provider_(new TestUpdatableResourceProvider) {}
 
 TestChromeBrowserProvider::~TestChromeBrowserProvider() {}
 
 // static
 TestChromeBrowserProvider* TestChromeBrowserProvider::GetTestProvider() {
   ChromeBrowserProvider* provider = GetChromeBrowserProvider();
   DCHECK(provider);
   return static_cast<TestChromeBrowserProvider*>(provider);
 }
 
 ChromeIdentityService* TestChromeBrowserProvider::GetChromeIdentityService() {
   return chrome_identity_service_.get();
 }
 
 UpdatableResourceProvider*
 TestChromeBrowserProvider::GetUpdatableResourceProvider() {
   return test_updatable_resource_provider_.get();
 }
 
 }  // namespace ios