Change GetAccessToken APIs so that they don't pass const ref to blocks.

ios/public/provider/chrome/browser/signin/chrome_identity_service.mm

 // Copyright 2015 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/signin/chrome_identity_service.h"
 
 #include "ios/public/provider/chrome/browser/signin/chrome_identity_interaction_manager.h"
 
 namespace ios {
 
@@ skipping 59 matching lines @@
   return nil;
 }
 
 NSArray* ChromeIdentityService::GetAllIdentitiesSortedForDisplay() const {
   return nil;
 }
 
 void ChromeIdentityService::ForgetIdentity(ChromeIdentity* identity,
                                            ForgetIdentityCallback callback) {}
 
-void ChromeIdentityService::GetAccessToken(
-    ChromeIdentity* identity,
-    const std::set<std::string>& scopes,
-    const AccessTokenCallback& callback) {}
+void ChromeIdentityService::GetAccessToken(ChromeIdentity* identity,
+                                           const std::set<std::string>& scopes,
+                                           AccessTokenCallback callback) {}
 
-void ChromeIdentityService::GetAccessToken(
-    ChromeIdentity* identity,
-    const std::string& client_id,
-    const std::string& client_secret,
-    const std::set<std::string>& scopes,
-    const AccessTokenCallback& callback) {}
+void ChromeIdentityService::GetAccessToken(ChromeIdentity* identity,
+                                           const std::string& client_id,
+                                           const std::string& client_secret,
+                                           const std::set<std::string>& scopes,
+                                           AccessTokenCallback callback) {}
 
 void ChromeIdentityService::GetAvatarForIdentity(ChromeIdentity* identity,
                                                  GetAvatarCallback callback) {}
 
 UIImage* ChromeIdentityService::GetCachedAvatarForIdentity(
     ChromeIdentity* identity) {
   return nil;
 }
 
 void ChromeIdentityService::GetHostedDomainForIdentity(
@@ skipping 39 matching lines @@
   for (auto& observer : observer_list_)
     observer.OnAccessTokenRefreshFailed(identity, user_info);
 }
 
 void ChromeIdentityService::FireProfileDidUpdate(ChromeIdentity* identity) {
   for (auto& observer : observer_list_)
     observer.OnProfileUpdate(identity);
 }
 
 }  // namespace ios