Access SigninErrorProvider through ChromeBrowserProvider.

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

 // Copyright 2016 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.
 
 #import "ios/public/provider/chrome/browser/signin/fake_chrome_identity_interaction_manager.h"
 
 #include "base/mac/scoped_block.h"
 #include "base/mac/scoped_nsobject.h"
+#import "ios/public/provider/chrome/browser/chrome_browser_provider.h"
 #import "ios/public/provider/chrome/browser/signin/fake_chrome_identity_service.h"
 #include "ios/public/provider/chrome/browser/signin/signin_error_provider.h"
 
 @interface FakeAddAccountViewController : UIViewController {
   FakeChromeIdentityInteractionManager* _manager;  // Weak.
   base::scoped_nsobject<UIButton> _cancelButton;
   base::scoped_nsobject<UIButton> _signInButton;
 }
 @end
 
@@ skipping 135 matching lines @@
   if (_completionCallback) {
     // Ensure self is not destroyed in the callback.
     base::scoped_nsobject<FakeChromeIdentityInteractionManager> strongSelf(
         [self retain]);
     _completionCallback.get()(error ? nil : _fakeIdentity, error);
     _completionCallback.reset();
   }
 }
 
 - (NSError*)canceledError {
-  ios::SigninErrorProvider* provider = ios::GetSigninErrorProvider();
+  ios::SigninErrorProvider* provider =
+      ios::GetChromeBrowserProvider()->GetSigninErrorProvider();
   return [NSError errorWithDomain:provider->GetSigninErrorDomain()
                              code:provider->GetCode(ios::SigninError::CANCELED)
                          userInfo:nil];
 }
 
 @end