Introduce FakeChromeIdentity and FakeChromeIdentityService.

ios/public/provider/chrome/browser/signin/fake_chrome_identity.h

+// 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.
+
+#ifndef IOS_PUBLIC_PROVIDER_CHROME_BROWSER_SIGNIN_FAKE_CHROME_IDENTITY_H_
+#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_SIGNIN_FAKE_CHROME_IDENTITY_H_
+
+#import "ios/public/provider/chrome/browser/signin/chrome_identity.h"
+
+// A fake ChromeIdentity used for testing.
+@interface FakeChromeIdentity : ChromeIdentity
+
+// Returns an autoreleased ChromeIdentity based on |email|, |gaiaID| and |name|.
+// The |hashedGaiaID| property will be derived from |name|.
++ (FakeChromeIdentity*)identityWithEmail:(NSString*)email
+                                  gaiaID:(NSString*)gaiaID
+                                    name:(NSString*)name;
+
+@end
+
+#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_SIGNIN_FAKE_CHROME_IDENTITY_H_