[Media Router] Design MediaRouter interface with stub implementation.

chrome/browser/media/router/media_route_response.h

+// Copyright 2015 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 CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_RESPONSE_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_RESPONSE_H_
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/media/router/media_route.h"
+
+namespace media_router {
+
+// Response from the media route provider to a media route request.
+class MediaRouteResponse {
+ public:
+  // Creates a MediaRouteResponse object that indicates success.
+  // |request_id|: ID of original request.
+  // |route|: Route created.
+  static scoped_ptr<MediaRouteResponse> CreateFromSuccess(
+      const RouteRequestId& request_id,
+      const MediaRoute& route);
+
+  // Creates a MediaRouteResponse object that indicates failure.
+  // |request_id|: ID of original request.
+  // |error|: Failure reason.
+  static scoped_ptr<MediaRouteResponse> CreateFromError(
+      const RouteRequestId& request_id,
+      const std::string& error);
+
+  ~MediaRouteResponse();
+
+  const RouteRequestId& request_id() const { return request_id_; }
+
+  // Returns the route created. Returns an empty route if response is error.

[mark a. foltz, 2015/03/31 22:10:24]

...created, or an empty route if there was an error.

[imcheng, 2015/04/01 00:55:16]

Done.

+  const MediaRoute& route() const { return route_; }
+
+  // Returns the error. Returns an empty string if response is success.

[mark a. foltz, 2015/03/31 22:10:24]

error, or an empty string if the route was created successfully.

[imcheng, 2015/04/01 00:55:16]

Done.

+  const std::string& error() const { return error_; }
+
+ private:
+  MediaRouteResponse(const RouteRequestId& request_id, const MediaRoute& route);
+  MediaRouteResponse(const RouteRequestId& request_id,
+                     const std::string& error);
+
+  // ID of original request. Set in all MediaRouteResponse objects, regardless

[mark a. foltz, 2015/03/31 22:10:24]

Since the documentation in the public API describes the different possible
values for the fields, I might shorten or omit these field-level comments. Up to
you though.

[imcheng, 2015/04/01 00:55:16]

Removed comment son route_ and error_.

+  // of success/failure.
+  const RouteRequestId request_id_;
+  // The route created as a result of the request. Set to a valid MediaRoute
+  // iff the response indicates success, empty MediaRoute otherwise.
+  const MediaRoute route_;
+  // Set to empty string if response indicates success, otherwise set to the
+  // failure reason.
+  const std::string error_;
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_RESPONSE_H_