[Media Router] Convert MediaRouter to use GURL for presentation URLs.

content/public/browser/presentation_session.cc

Index: content/public/browser/presentation_session.cc
diff --git a/content/public/browser/presentation_session.cc b/content/public/browser/presentation_session.cc
index cf6111da59e929db41e2d759841c3ff6b01af69d..ceca42d9f895fd37093852e491022a92650c13af 100644
--- a/content/public/browser/presentation_session.cc
+++ b/content/public/browser/presentation_session.cc
@@ -7,11 +7,9 @@
 namespace content {
 
 PresentationSessionInfo::PresentationSessionInfo(
-    const std::string& presentation_url,
+    const GURL& presentation_url,
     const std::string& presentation_id)
-    : presentation_url(presentation_url),
-      presentation_id(presentation_id) {
-}
+    : presentation_url(presentation_url), presentation_id(presentation_id) {}
 
 PresentationSessionInfo::~PresentationSessionInfo() {
 }