Add media router common classes and unittests.

chrome/browser/media/router/media_route.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_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_H_
+
+#include <string>
+
+#include "base/gtest_prod_util.h"
+#include "base/logging.h"
+#include "base/values.h"
+#include "chrome/browser/media/router/media_route_id.h"
+#include "chrome/browser/media/router/media_sink.h"
+#include "chrome/browser/media/router/media_source.h"
+#include "url/gurl.h"
+
+namespace media_router {
+
+using RouteRequestId = int64;
+
+extern const RouteRequestId kInvalidRouteRequestId;
+
+class MediaRouteFactory;
+
+// For now, a simple transition graph: NEW -> CONNECTED -> CLOSED.
+enum MediaRouteState {
+  // The route is new and not yet connected to a sink.
+  MEDIA_ROUTE_STATE_NEW,
+  // The route is active and connected to a sink.
+  MEDIA_ROUTE_STATE_CONNECTED,
+  // The route has been disconnected.
+  MEDIA_ROUTE_STATE_CLOSED
+};
+
+// A MediaRoute encapsulates an application's means of routing media from a
+// source to a sink.
+class MediaRoute {
+ public:
+  ~MediaRoute();
+
+  // The media route identifier.
+  const MediaRouteId& media_route_id() const { return media_route_id_; }
+
+  // The state of the media route.
+  MediaRouteState state() const { return state_; }
+
+  // The media source being routed.
+  const MediaSource& media_source() const { return media_source_; }

[imcheng, 2015/03/03 22:53:09]

It's not hard to misuse a getter that returns by reference to a member variable.
What do you think if we just return by value all the time and make it consistent
throughout the code?

[Kevin M, 2015/03/03 23:28:05]

I think returning field const references is widespread and generally accepted as
safe...

I did a pass to ensure that we're being consistent with our use of references
for non-POD data.

+
+  // The ID of the sink being routed to.
+  const MediaSinkId& sink_id() const { return sink_id_; }
+
+  // The description of the media route activity, for example
+  // "Playing Foo Bar Music All Access."
+  // TODO(kmarshall): Does this need to be localized?

[mark a. foltz, 2015/03/04 06:22:59]

Per discussion, the browser is not responsible for localizing this, the
extension is. However, without the locale included, we may not be able to render
it correctly (e.g. LTR or RTL).

I might update this TODO to say "Do we need to pass locale information?"

[Kevin M, 2015/03/04 23:33:32]

I hadn't considered the bidi aspect. OK, TODO added. Thanks.

+  const std::string& description() const { return description_; }
+
+  // Returns |true| if the route is created locally (versus diescovered

[mark a. foltz, 2015/03/04 06:22:59]

discovered

[Kevin M, 2015/03/04 23:33:32]

Done.

+  // by a media route provider.)
+  bool is_local() const { return is_local_; }
+
+  bool operator==(const MediaRoute& other) const;
+  bool operator!=(const MediaRoute& other) const;
+
+ private:
+  friend class MediaRouteFactory;
+  FRIEND_TEST_ALL_PREFIXES(MediaRouteTest, Equals);
+
+  // |media_route_id|: Uniquely identifies the route among active
+  // instances for this media source.
+  // |type|: Type of media route.
+  // |media_source|: Description of source of the route.
+  // |sink_id|: ID of the MediaSink of the route.
+  // |description|: Description of the route to be displayed.
+  // |is_local|: true if the route was created from this browser.
+  MediaRoute(const MediaRouteId& media_route_id,
+             const MediaSource& media_source,
+             const MediaSinkId& sink_id,
+             const std::string& description,
+             bool is_local);
+
+  const MediaRouteId media_route_id_;
+  const MediaSource media_source_;
+  const MediaSinkId sink_id_;
+  const std::string description_;
+  const bool is_local_;
+  const MediaRouteState state_;
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_H_