Implement the Sync promo in the password bubble on Mac.

chrome/browser/ui/cocoa/passwords/signin_promo_view_controller.h

Index: chrome/browser/ui/cocoa/passwords/signin_promo_view_controller.h
diff --git a/chrome/browser/ui/cocoa/passwords/signin_promo_view_controller.h b/chrome/browser/ui/cocoa/passwords/signin_promo_view_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..b5167335e7ad1b5f53cbf30733e480f138e67d94
--- /dev/null
+++ b/chrome/browser/ui/cocoa/passwords/signin_promo_view_controller.h
@@ -0,0 +1,25 @@
+// 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_UI_COCOA_PASSWORDS_SIGNIN_PROMO_VIEW_CONTROLLER_H_
+#define CHROME_BROWSER_UI_COCOA_PASSWORDS_SIGNIN_PROMO_VIEW_CONTROLLER_H_
+
+#import <Cocoa/Cocoa.h>
+
+#import "chrome/browser/ui/cocoa/passwords/base_passwords_content_view_controller.h"
+
+// A view controller that offers user to sign in to Chrome.
+@interface SignInPromoViewController
+    : BasePasswordsContentViewController
+
+- (instancetype)initWithDelegate:(id<BasePasswordsContentViewDelegate>)delegate;
+
+@end
+
+@interface SignInPromoViewController (Testing)
+@property(readonly) NSButton* signInButton;
+@property(readonly) NSButton* noButton;
+@end
+
+#endif  // CHROME_BROWSER_UI_COCOA_PASSWORDS_SIGNIN_PROMO_VIEW_CONTROLLER_H_