Media Session API: use MediaMetadata in the browser process.

content/browser/media/session/media_session.h

Index: content/browser/media/session/media_session.h
diff --git a/content/browser/media/session/media_session.h b/content/browser/media/session/media_session.h
index 4fb5d42af49f51096ea855204f4411ad997bfef2..2553c6d7885d58e9b1159201568cdb02d7f9256d 100644
--- a/content/browser/media/session/media_session.h
+++ b/content/browser/media/session/media_session.h
@@ -13,6 +13,7 @@
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
+#include "content/public/common/media_metadata.h"
 
 class MediaSessionBrowserTest;
 
@@ -58,6 +59,11 @@ class MediaSession : public WebContentsObserver,
 
   ~MediaSession() override;
 
+  void setMetadata(const MediaMetadata& metadata) {
+    metadata_ = metadata;
+  }
+  const MediaMetadata& metadata() const { return metadata_; }
+
   // Adds the given player to the current media session. Returns whether the
   // player was successfully added. If it returns false, AddPlayer() should be
   // called again later.
@@ -184,6 +190,8 @@ class MediaSession : public WebContentsObserver,
   // multiply their volume with this multiplier to get the effective volume.
   double volume_multiplier_;
 
+  MediaMetadata metadata_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaSession);
 };