Wrap MediaMetadata in base::Optional in content and chrome

content/browser/android/web_contents_observer_proxy.h

Index: content/browser/android/web_contents_observer_proxy.h
diff --git a/content/browser/android/web_contents_observer_proxy.h b/content/browser/android/web_contents_observer_proxy.h
index af0895dc6693f3ea23fdda5d44268333e38b0639..8888f538dbcfd5c143395318e9b7ec39d1fec316 100644
--- a/content/browser/android/web_contents_observer_proxy.h
+++ b/content/browser/android/web_contents_observer_proxy.h
@@ -72,9 +72,10 @@ class WebContentsObserverProxy : public WebContentsObserver {
   void DidStartNavigationToPendingEntry(
       const GURL& url,
       NavigationController::ReloadType reload_type) override;
-  void MediaSessionStateChanged(bool is_controllable,
-                                bool is_suspended,
-                                const MediaMetadata& metadata) override;
+  void MediaSessionStateChanged(
+      bool is_controllable,
+      bool is_suspended,
+      const base::Optional<MediaMetadata>& metadata) override;
   void SetToBaseURLForDataURLIfNeeded(std::string* url);
 
   void DidFailLoadInternal(bool is_provisional_load,