[Autofill] Add support for signin promo on Android

chrome/browser/signin/signin_promo_util.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 CHROME_BROWSER_SIGNIN_SIGNIN_PROMO_UTIL_H_
+#define CHROME_BROWSER_SIGNIN_SIGNIN_PROMO_UTIL_H_
+
+class Profile;
+
+// Cross-platform utility functions for signin promos.
+namespace signin {
+
+// Returns true if the sign in promo should be visible.
+// |profile| is the profile of the tab the promo would be shown on.
+bool ShouldShowPromo(Profile* profile);
+
+}  // namespace signin
+
+#endif  // CHROME_BROWSER_SIGNIN_SIGNIN_PROMO_UTIL_H_