[Presentation API] 1-UA: send message between controller and receiver page

content/public/browser/presentation_service_delegate.h

Index: content/public/browser/presentation_service_delegate.h
diff --git a/content/public/browser/presentation_service_delegate.h b/content/public/browser/presentation_service_delegate.h
index 2f981aa7dc4b97a834efbbb8b1f5bc4fa71e9b69..302a1fb9048181b597f8eb6897d404436994bcbd 100644
--- a/content/public/browser/presentation_service_delegate.h
+++ b/content/public/browser/presentation_service_delegate.h
@@ -52,6 +52,11 @@ class OffscreenPresentationClient {
  public:
   OffscreenPresentationClient() {}
 
+  virtual void OnSessionMessages(
+      const content::PresentationSessionInfo& session,
+      const ScopedVector<PresentationSessionMessage>& messages,
+      bool pass_ownership) = 0;
+
   // For controller, add a receiver client
   // For receiver, add a controller client
   virtual void SetOffscreenPresentationClient(OffscreenPresentationClient*) = 0;