Adding mediator for Sign-in promo

ios/chrome/browser/ui/authentication/signin_promo_view.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_SIGN_PROMO_VIEW_H_
+#define IOS_CHROME_BROWSER_UI_AUTHENTICATION_SIGN_PROMO_VIEW_H_
+
+#import <UIKit/UIKit.h>
+
+@class MDCFlatButton;
+@class SigninPromoView;
+
+// Configures a SigninPromoView view.
+@protocol SigninPromoViewConfigurator<NSObject>
+
+- (void)configureSigninPromoView:(SigninPromoView*)signinPromoView;
+
+@end
+
+typedef NS_ENUM(NSInteger, SigninPromoViewMode) {
+  // No identity available on the device.
+  SigninPromoViewModeColdState,
+  // At least one identity is available on the device and the user can sign
+  // without entering their credentials.
+  SigninPromoViewModeWarmState,
+};
+
+// This class creates an image view, a label and 2 buttons. This view can be
+// configured with 2 modes : "Cold State" and "Warm State".
+// + "Cold State" mode displays the chomium icon in the image view, and only
+//   displays the primary button.
+// + "Warm State" mode displays the image view (big than the cold state mode),
+//   displays both buttons.
+//
+//  For the warm state, the owner should set:
+//   - the image for |imageView|, using -[SigninPromoView setProfileImage:]
+//   - the label for |textLabel|
+//   - the title for |primaryButton|
+//   - the title for |secondaryButton|
+@interface SigninPromoView : UIView
+
+@property(nonatomic) SigninPromoViewMode mode;
+@property(nonatomic, readonly) UIImageView* imageView;
+@property(nonatomic, readonly) UILabel* textLabel;
+@property(nonatomic, readonly) MDCFlatButton* primaryButton;
+@property(nonatomic, readonly) MDCFlatButton* secondaryButton;
+
+// Horizontal padding used for |textLabel|, |primaryButton| and
+// |secondaryButton|. Used to compute the preferred max layout width of
+// |textLabel|.
+@property(nonatomic, readonly) CGFloat horizontalPadding;
+
+- (instancetype)initWithCoder:(NSCoder*)aDecoder NS_UNAVAILABLE;
+
+// Sets the image in |imageView|. This method will add a circular background
+// using CircularImageFromImage() (so if the image is not squared, it will be
+// cropped first). Must only be called in the "Warm State" mode.
+- (void)setProfileImage:(UIImage*)image;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_AUTHENTICATION_SIGN_PROMO_VIEW_H_