[MediaRouter] Add implementation of PresentationServiceDelegate

chrome/browser/media/router/media_source_helper.cc

Index: chrome/browser/media/router/media_source_helper.cc
diff --git a/chrome/browser/media/router/media_source_helper.cc b/chrome/browser/media/router/media_source_helper.cc
index 305a00fa3437dd83fa5b8eba3de0bdb61e65380c..988709d9f11d8f5661e661c397365fc045bea4c2 100644
--- a/chrome/browser/media/router/media_source_helper.cc
+++ b/chrome/browser/media/router/media_source_helper.cc
@@ -17,21 +17,19 @@ const char kTabMediaUrnPrefix[] = "urn:x-org.chromium.media:source:tab";
 const char kDesktopMediaUrn[] = "urn:x-org.chromium.media:source:desktop";
 const char kCastUrnPrefix[] = "urn:x-com.google.cast:application:";
 
-MediaSource ForTabMediaSource(int tab_id) {
+MediaSource MediaSourceForTab(int tab_id) {
   return MediaSource(base::StringPrintf("%s:%d", kTabMediaUrnPrefix, tab_id));
 }
 
-MediaSource ForDesktopMediaSource() {
+MediaSource MediaSourceForDesktop() {
   return MediaSource(std::string(kDesktopMediaUrn));
 }
 
-// TODO(mfoltz): Remove when the TODO in
-// MediaSourceManager::GetDefaultMediaSource is resolved.
-MediaSource ForCastAppMediaSource(const std::string& app_id) {
+MediaSource MediaSourceForCastApp(const std::string& app_id) {
   return MediaSource(kCastUrnPrefix + app_id);
 }
 
-MediaSource ForPresentationUrl(const std::string& presentation_url) {
+MediaSource MediaSourceForPresentationUrl(const std::string& presentation_url) {
   return MediaSource(presentation_url);
 }
 
@@ -49,4 +47,8 @@ bool IsValidMediaSource(const MediaSource& source) {
   return url.is_valid() && url.SchemeIsHTTPOrHTTPS();
 }
 
+std::string PresentationUrlFromMediaSource(const MediaSource& source) {
+  return IsValidPresentationUrl(source.id()) ? source.id() : "";
+}
+
 }  // namespace media_router