Create an Obj-C bridge for MostVisitedSitesObserver

components/ntp_tiles/ios/most_visited_sites_bridge_observer.h

+// Copyright 2017 The Chromium Authors. All rights reserved.

[sdefresne, 2017/04/03 14:25:49]

I think this file should be named after the main class, so
most_visited_sites_bridge.h or if you rename the class as suggested
most_visited_sites_observer_bridge.h.

[gambard, 2017/04/03 15:17:36]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_NTP_TILES_IOS_MOST_VISITED_SITES_BRIDGE_OBSERVER_H_
+#define COMPONENTS_NTP_TILES_IOS_MOST_VISITED_SITES_BRIDGE_OBSERVER_H_
+
+#import <Foundation/Foundation.h>
+
+#include "components/ntp_tiles/most_visited_sites.h"
+
+// Observes MostVisitedSites events from Objective-C. To use as a
+// ntp_tiles::MostVisitedSites::Observer, wrap in a MostVisitedSitesBridge.
+@protocol MostVisitedSitesObserver

[sdefresne, 2017/04/03 14:25:49]

marq & rohitrao recommendation regarding Objective-C protocol to bridge C++
observer interfaces would be to name this @protocol MostVisitedSitesObserving.

[gambard, 2017/04/03 15:17:36]

Done.

+
+// Invoked by ntp_tiles::MostVisitedSites::Observer::OnMostVisitedURLsAvailable.
+- (void)onMostVisitedURLsAvailable:
+    (const ntp_tiles::NTPTilesVector&)mostVisited;
+
+// Invoked by ntp_tiles::MostVisitedSites::Observer::OnIconMadeAvailable.
+- (void)onIconMadeAvailable:(const GURL&)siteURL;
+
+@end
+
+namespace ntp_tiles {
+
+// Observer for the MostVisitedSites that translates all the callbacks to
+// Objective-C calls.
+class MostVisitedSitesBridge : public MostVisitedSites::Observer {

[sdefresne, 2017/04/03 14:25:49]

I would call this MostVisitedSitesObserverBridge.

[gambard, 2017/04/03 15:17:37]

Done.

+ public:
+  MostVisitedSitesBridge(id<MostVisitedSitesObserver> observer);
+
+  void OnMostVisitedURLsAvailable(const NTPTilesVector& most_visited) override;
+  void OnIconMadeAvailable(const GURL& site_url) override;
+
+ private:
+  __unsafe_unretained id<MostVisitedSitesObserver> observer_;

[sdefresne, 2017/04/03 14:25:49]

I think we should avoid using __unsafe_unretained if possible, what about using
base::WeakNSProtocol<id<MostvisitedSitesObserver>> here?

[gambard, 2017/04/03 15:17:36]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(MostVisitedSitesBridge);
+};
+
+}  // namespace ntp_tiles
+
+#endif  // COMPONENTS_NTP_TILES_IOS_MOST_VISITED_SITES_BRIDGE_OBSERVER_H_