[Media Router] Design MediaRouter interface with stub implementation.

chrome/browser/media/router/media_sink.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_SINK_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_SINK_H_
 
 #include <string>
 
 #include "chrome/browser/media/router/media_route_id.h"
 
 namespace media_router {
 
 using MediaSinkId = std::string;
 
 // Represents a sink to which media can be routed.
 class MediaSink {
  public:
   // |sink_id|: Unique identifier for the MediaSink.
   // |name|: Descriptive name of the MediaSink.
+  //         Optional, can use an empty string if no sink name is available.
   MediaSink(const MediaSinkId& sink_id,
             const std::string& name);
+
+  // Constructs an empty MediaSink.
+  MediaSink();

[xhwang, 2015/04/06 20:51:31]

What's the use case of an empty MediaSink?

[imcheng, 2015/04/06 21:54:20]

Removed for now.

+
   ~MediaSink();
 
-  const MediaSinkId& sink_id() const { return sink_id_; }
+  const MediaSinkId& id() const { return sink_id_; }
   const std::string& name() const { return name_; }
 
   bool Equals(const MediaSink& other) const;
+  bool Empty() const;
 
  private:
-  const MediaSinkId sink_id_;
-  const std::string name_;
+  MediaSinkId sink_id_;
+  std::string name_;

[xhwang, 2015/04/06 20:51:31]

Here and for all other classes, consider DISALLOW_COPY_AND_ASSIGN wherever
applicable.

[xhwang, 2015/04/06 20:51:31]

Why drop the "const", is MediaSink() mutable now?

[xhwang, 2015/04/06 20:51:31]

These are both strings. What's the difference?

[imcheng, 2015/04/06 21:54:20]

From the API perspective MediaSink is still immutable. However I had to remove
the const qualifiers in order to support copy-assignment, which appears to be
used by STL implementation.

[imcheng, 2015/04/06 21:54:20]

The ID is internal to the system and is what the code uses to identify a sink.
The name is a description of the sink and is intended to be user-facing.

[imcheng, 2015/04/06 21:54:20]

These need to be copyable because they are put into stl containers.

 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_SINK_H_