Add media router common classes and unittests.

chrome/browser/media/router/media_source_unittest.cc

Index: chrome/browser/media/router/media_source_unittest.cc
diff --git a/chrome/browser/media/router/media_source_unittest.cc b/chrome/browser/media/router/media_source_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..470b5728b6c24f4572038c45b0882d08de00656e
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+++ b/chrome/browser/media/router/media_source_unittest.cc
@@ -0,0 +1,16 @@
+// 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_source.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media_router {
+
+// Test that the object's getters match the constructor parameters.
+TEST(MediaSourceTest, Constructor) {
+  MediaSource source1("urn:x-com.google.cast:application:DEADBEEF");
+  EXPECT_EQ("urn:x-com.google.cast:application:DEADBEEF", source1.id());
+}
+
+}  // namespace media_router