media: Use new wrapper types for media mojo interfaces

media/base/media_keys.h

Index: media/base/media_keys.h
diff --git a/media/base/media_keys.h b/media/base/media_keys.h
index 6e094af5a857c45522f1018171df29a6589e426e..98489fd8d3eac81285b97d3ad3fa8851d3144849 100644
--- a/media/base/media_keys.h
+++ b/media/base/media_keys.h
@@ -121,7 +121,11 @@ class MEDIA_EXPORT MediaKeys
       const std::vector<uint8_t>& init_data,
       std::unique_ptr<NewSessionCdmPromise> promise) = 0;
 
-  // Loads a session with the |session_id| provided.
+  // Loads a session with the |session_id| provided. Resolves the |promise| with
+  // |session_id| if the session is successfully loaded. Resolves the |promise|
+  // with an empty session ID if the session cannot be found. Rejects the
+  // |promise| if session loading is not supported, or other unexpected failure
+  // happened.
   // Note: UpdateSession(), CloseSession() and RemoveSession() should only be
   //       called after the |promise| is resolved.
   virtual void LoadSession(SessionType session_type,