Move impl of identity.GetAuthToken() extension API to its own file

chrome/browser/extensions/api/identity/identity_apitest.cc

 // Copyright (c) 2012 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 <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_util.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "components/prefs/pref_service.h"
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/login/users/mock_user_manager.h"
 #include "chrome/browser/chromeos/login/users/scoped_user_manager_enabler.h"
 #include "chrome/browser/chromeos/policy/browser_policy_connector_chromeos.h"
 #include "chrome/browser/chromeos/settings/stub_install_attributes.h"
 #include "extensions/common/extension_builder.h"
 #endif
 #include "chrome/browser/extensions/api/identity/identity_api.h"
 #include "chrome/browser/extensions/api/identity/identity_constants.h"
+#include "chrome/browser/extensions/api/identity/identity_get_auth_token_function.h"
 #include "chrome/browser/extensions/api/identity/identity_get_profile_user_info_function.h"
 #include "chrome/browser/extensions/api/identity/identity_launch_web_auth_flow_function.h"
 #include "chrome/browser/extensions/api/identity/identity_remove_cached_auth_token_function.h"
 #include "chrome/browser/extensions/component_loader.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "chrome/browser/extensions/extension_function_test_utils.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/account_tracker_service_factory.h"
@@ skipping 1820 matching lines @@
   EXPECT_EQ(std::string("https://abcdefghij.chromiumapp.org/callback#test"),
             url);
 }
 
 }  // namespace extensions
 
 // Tests the chrome.identity API implemented by custom JS bindings .
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, ChromeIdentityJsBindings) {
   ASSERT_TRUE(RunExtensionTest("identity/js_bindings")) << message_;
 }