Creates FaviconAttributesProvider.

ios/chrome/browser/favicon/favicon_attributes.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_CHROME_BROWSER_FAVICON_FAVICON_ATTRIBUTES_H_
+#define IOS_CHROME_BROWSER_FAVICON_FAVICON_ATTRIBUTES_H_
+
+#import <UIKit/UIKit.h>
+
+// Attributes of a favicon. A favicon is represented either with an image or
+// with a fallback monogram of a given color and background color.

[noyau (Ping after 24h), 2016/10/03 14:52:10]

CL https://codereview.chromium.org/2374753002/ introduces the notion of favicon
style which seems to encompass the same data. Can't you reuse it?

[stkhapugin, 2016/10/04 11:47:18]

There seems to only be a "fallback favicon style", not "favicon style".
Also, this class exposes a UIKit-friendly API. I can create a convenience
initializer that takes a FallbackIconStyle, but I'd prefer to keep this API to
make view code cleaner. 

+@interface FaviconAttributes : NSObject
+
+// Favicon image. Can be nil. If it is nil, monogram string and color are
+// guaranteed to be not nil.
+@property(nonatomic, readonly, strong) UIImage* faviconImage;
+// Favicon monogram. Only available when there is no image.
+@property(nonatomic, readonly, copy) NSString* monogramString;
+// Favicon monogram color. Only available when there is no image.
+@property(nonatomic, readonly, strong) UIColor* textColor;
+// Favicon monogram background color. Only available when there is no image.
+@property(nonatomic, readonly, strong) UIColor* backgroundColor;
+
++ (instancetype)attributesWithImage:(UIImage*)image;
++ (instancetype)attributesWithMonogram:(NSString*)monogram
+                             textColor:(UIColor*)textColor
+                       backgroundColor:(UIColor*)backgroundColor;
+
+// Designated initializer. Either |image| or all of |textColor|,
+// |backgroundColor| and |monogram| must be not nil.
+- (instancetype)initWithImage:(UIImage*)image
+                     monogram:(NSString*)monogram
+                    textColor:(UIColor*)textColor
+              backgroundColor:(UIColor*)backgroundColor
+    NS_DESIGNATED_INITIALIZER;
+- (instancetype)initWithImage:(UIImage*)image;
+- (instancetype)initWithMonogram:(NSString*)monogram
+                       textColor:(UIColor*)textColor
+                 backgroundColor:(UIColor*)backgroundColor;
+
+- (instancetype)init NS_UNAVAILABLE;
+@end
+
+#endif  // IOS_CHROME_BROWSER_FAVICON_FAVICON_ATTRIBUTES_H_