[Presentation API] Plumbing the |defaultpresentationstart| event from Blink to browser/Mojo.

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 "base/logging.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/render_frame_host.h"
@@ skipping 81 matching lines @@
         std::make_pair(presentation_url_str, context)).first;
   }
 
   it->second->CallbackReceived(callback);
 }
 
 void PresentationServiceImpl::OnScreenAvailabilityListenerRemoved() {
   NOTIMPLEMENTED();
 }
 
+void PresentationServiceImpl::ListenForDefaultSessionStart(
+    const DefaultSessionMojoCallback& callback) {
+  NOTIMPLEMENTED();
+}
+
 void PresentationServiceImpl::StartSession(
     const mojo::String& presentation_url,
     const mojo::String& presentation_id,
     const NewSessionMojoCallback& callback) {
   NOTIMPLEMENTED();
 }
 
 void PresentationServiceImpl::JoinSession(
     const mojo::String& presentation_url,
     const mojo::String& presentation_id,
@@ skipping 97 matching lines @@
   } else {
     // Invoke callback and erase it.
     // There shouldn't be any result stored in this scenario.
     DCHECK(!available_ptr_);
     callback_ptr_->Run(available);
     Reset();
   }
 }
 
 }  // namespace content