[MediaRouter] Add implementation of PresentationServiceDelegate

chrome/browser/media/router/media_source_helper_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_source.h"
 #include "chrome/browser/media/router/media_source_helper.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace media_router {
 
@@ skipping 22 matching lines @@
   EXPECT_TRUE(IsValidMediaSource(ForPresentationUrl("http://example.com/")));
   EXPECT_TRUE(IsValidMediaSource(ForPresentationUrl("https://example.com/")));
 
   // Disallowed scheme
   EXPECT_FALSE(
       IsValidMediaSource(ForPresentationUrl("file:///some/local/path")));
   // Not a URL
   EXPECT_FALSE(IsValidMediaSource(ForPresentationUrl("totally not a url")));
 }
 
+TEST(MediaSourcesTest, GetPresentationUrl) {
+  EXPECT_EQ("", GetPresentationUrl(ForTabMediaSource(123)));
+  EXPECT_EQ("", GetPresentationUrl(ForDesktopMediaSource()));
+  EXPECT_EQ("http://example.com/",
+            GetPresentationUrl(ForPresentationUrl("http://example.com/")));
+}
+
 }  // namespace media_router