Adding mediator for Sign-in promo

ios/chrome/browser/ui/authentication/signin_promo_view_mediator.h

+// Copyright 2017 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_CHROME_BROWSER_UI_AUTHENTICATION_SIGNIN_PROMO_VIEW_MEDIATOR_H_
+#define IOS_CHROME_BROWSER_UI_AUTHENTICATION_SIGNIN_PROMO_VIEW_MEDIATOR_H_
+
+#import <Foundation/Foundation.h>
+
+#import "ios/chrome/browser/ui/authentication/signin_promo_view.h"
+
+// Class that configures a SigninPromoView instance. This class is a simple
+// implementation that only stores data.
+// TODO(jlebel): Create a subclass that monitor profile notification.

[lpromero, 2017/03/24 10:36:20]

monitors
presubmit will also ask you to change the TODO format to TODO(crbug.com/xxxxx)

[jlebel, 2017/03/24 20:59:09]

Done.

+@interface SigninPromoViewMediator : NSObject<SigninPromoViewConfigurator>
+
+@property(nonatomic, copy) NSString* userFullName;

[msarda, 2017/03/22 12:18:39]

My understanding is that the mediator mediates between the model and the view.
If so, then the mediator should use a ChromeIdentity and the
ChromeIdentityService.

Let's wait for Louis' review though.

[lpromero, 2017/03/22 16:18:49]

Right, the mediator is not part of the UI layer, and it speaks both the model
and UI language. You can init it with a ChromeIdentity for example, and it
sources strings to the UI when asked.

Mediator is usually an actor, not just a data holder. It handles the translation
from ChromeIdentity to strings/images.

[jlebel, 2017/03/24 20:59:09]

The ProfileSigninPromoViewMediator will be able to handle a ChromeIdentity.
See crrev.com/2750403003

[msarda, 2017/03/27 09:34:16]

I do not understand the interest of having a SigninPromoViewMediator and a
ProfileSigninPromoViewMediator in folder ios/chrome/browser/ui/authentication/ -
there should be only one here and it must use the ChromeIdentity objects.

If there is a need for a specialized SigninPromoViewMediator in the cell
catalog, then this class should be moved in that folder and only used there (I
want us to avoid subclassing for the mediator as this adds unnecessary
complexity that we'll have to maintain in the future).

[lpromero, 2017/03/27 13:14:46]

Agreed. The cell catalog should not add complexity.

+@property(nonatomic, copy) NSString* userEmail;
+@property(nonatomic, copy) UIImage* userImage;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_AUTHENTICATION_SIGNIN_PROMO_VIEW_MEDIATOR_H_