Creates FaviconAttributesProvider.

ios/chrome/browser/favicon/favicon_attributes_provider.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_PROVIDER_H_
+#define IOS_CHROME_BROWSER_FAVICON_FAVICON_ATTRIBUTES_PROVIDER_H_
+
+#import <UIKit/UIKit.h>
+#import "ios/chrome/browser/favicon/favicon_attributes.h"

[noyau (Ping after 24h), 2016/10/04 12:05:58]

Probably not needed, could be replaced by @class.

+
+namespace favicon {
+class LargeIconService;
+}  // namespace favicon
+
+@class FaviconViewProvider;
+class GURL;
+
+// Object to fetch favicon attributes by URL - an image or a fallback icon if
+// there is no favicon image available with large enough resolution.
+@interface FaviconAttributesProvider : NSObject

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

Can't this object be C++?

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

This is basically a UIKit-friendly ObjC wrapper for favicon::LargeIconService to
keep the rest of the code cleaner, as we don't have to do Skia->UIColor
conversions and bitmap data to UIImage conversions elsewhere. Just look at the
list of #includes in .mm that we mostly don't need elsewhere thanks to this
class.

[noyau (Ping after 24h), 2016/10/04 12:05:58]

I'm not arguing the utility of this class, which hides conversions as you said.
All I'm saying is that the API of this class has no dependencies on ObjectiveC,
the only reason you include UIKit it for NSObject. The .h could be C++ only. The
implementation needs to be a .mm file, for sure, but it doesn't need to be an
objectiveC class.

But what I missed the first time is that Faviconattribute is full of ObjectiveC
objects, this makes my point moot really.

+// Favicon attributes associated with |URL| will be fetched using
+// |largeIconService|. The favicon will be rendered with height and width equal
+// to |faviconSize|, and the image will be fetched if the source size is greater
+// than or equal to |minFaviconSize|.
+- (instancetype)initWithFaviconSize:(CGFloat)faviconSize
+                     minFaviconSize:(CGFloat)minFaviconSize
+                   largeIconService:(favicon::LargeIconService*)largeIconService
+    NS_DESIGNATED_INITIALIZER;
+- (instancetype)init NS_UNAVAILABLE;
+
+// Fetches favicon attributes and calls the completion block.
+- (void)fetchFaviconAttributesForURL:(const GURL&)URL
+                          completion:(void (^)(FaviconAttributes*))completion;
+
+// LargeIconService used to fetch favicons.
+@property(nonatomic, readonly) favicon::LargeIconService* largeIconService;
+// Minimal acceptable favicon size. Below that, will fall back to a monogram.
+@property(nonatomic, readonly) CGFloat minSize;
+// Expected favicon size (in points). Will downscale favicon to this.
+@property(nonatomic, readonly) CGFloat faviconSize;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_FAVICON_FAVICON_ATTRIBUTES_PROVIDER_H_