[PresentationAPI] Added on-session-message handler.

content/browser/presentation/presentation_service_impl.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/presentation/presentation_service_impl.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "content/browser/presentation/presentation_type_converters.h"
@@ skipping 315 matching lines @@
 
 bool PresentationServiceImpl::FrameMatches(
     content::RenderFrameHost* render_frame_host) const {
   if (!render_frame_host)
     return false;
 
   return render_frame_host->GetProcess()->GetID() == render_process_id_ &&
          render_frame_host->GetRoutingID() == render_frame_id_;
 }
 
+void PresentationServiceImpl::ListenForSessionMessages(
+    const SessionMessagesCallback& callback) {
+  NOTIMPLEMENTED();
+}
+
 void PresentationServiceImpl::DidNavigateAnyFrame(
     content::RenderFrameHost* render_frame_host,
     const content::LoadCommittedDetails& details,
     const content::FrameNavigateParams& params) {
   DVLOG(2) << "PresentationServiceImpl::DidNavigateAnyFrame";
   if (!FrameMatches(render_frame_host))
     return;
 
   std::string prev_url_host = details.previous_url.host();
   std::string curr_url_host = params.url.host();
@@ skipping 179 matching lines @@
 void PresentationServiceImpl::DefaultSessionStartContext::Reset() {
   ScopedVector<DefaultSessionMojoCallback> callbacks;
   callbacks.swap(callbacks_);
   for (const auto& callback : callbacks)
     callback->Run(presentation::PresentationSessionInfoPtr());
   session_.reset();
 }
 
 }  // namespace content