[Presentation API] Plumbing of |onstatechange| from the Mojo service to the public/platform

content/browser/presentation/presentation_service_impl.cc

Index: content/browser/presentation/presentation_service_impl.cc
diff --git a/content/browser/presentation/presentation_service_impl.cc b/content/browser/presentation/presentation_service_impl.cc
index 9efeb5f8d13664acc45d469c8e23a5020001ae7a..ee3943c6a5382476fee4f037d6b26ce520cdd6b8 100644
--- a/content/browser/presentation/presentation_service_impl.cc
+++ b/content/browser/presentation/presentation_service_impl.cc
@@ -262,6 +262,11 @@ void PresentationServiceImpl::CloseSession(
   NOTIMPLEMENTED();
 }
 
+void PresentationServiceImpl::ListenForSessionStateChange(
+    const SessionStateCallback& callback) {
+  NOTIMPLEMENTED();
+}
+
 void PresentationServiceImpl::DidNavigateAnyFrame(
     content::RenderFrameHost* render_frame_host,
     const content::LoadCommittedDetails& details,