Add media router common classes and unittests.

chrome/browser/media/router/media_sink_unittest.cc

+// 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.
+
+#include "chrome/browser/media/router/media_sink.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace media_router {
+
+TEST(MediaSinkTest, Equals) {
+  MediaSink sink1("sinkId", "Sink");
+
+  // Same as sink1.
+  MediaSink sink2("sinkId", "Sink");
+  EXPECT_TRUE(sink1.Equals(sink2));
+
+  // Sink name is different from sink1's.
+  MediaSink sink3("sinkId", "Other Sink");
+  EXPECT_TRUE(sink1.Equals(sink3));
+
+  // Sink ID is diffrent from sink1's.
+  MediaSink sink4("otherSinkId", "Sink");
+  EXPECT_FALSE(sink1.Equals(sink4));
+}
+
+}  // namespace media_router