[Presentation API] 1-UA: notify receiver page when receiver connection becomes available (blink sid…

third_party/WebKit/Source/modules/presentation/Presentation.cpp

 // Copyright 2014 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 "modules/presentation/Presentation.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
 #include "modules/presentation/PresentationController.h"
 #include "modules/presentation/PresentationReceiver.h"
@@ skipping 38 matching lines @@
         return;
 
     PresentationController* controller = PresentationController::from(*frame());
     if (!controller)
         return;
     controller->setDefaultRequestUrl(request ? request->url() : KURL());
 }
 
 PresentationReceiver* Presentation::receiver()
 {
+    PresentationController* controller = PresentationController::from(*frame());
+    auto client = controller ? controller->client() : nullptr;

[mark a. foltz, 2016/09/15 16:53:18]

It looks like this can only be nullptr if Presentation API is disabled as a
runtime feature.

It would clean up a lot of these extra checks if we could assume it was always
enabled.   Can we assume that now Mounir?

[zhaobin, 2016/09/15 18:56:03]

Acknowledged.

     // TODO(mlamouri): only return something if the Blink instance is running in
     // presentation receiver mode. The flag PresentationReceiver could be used
     // for that.

[mark a. foltz, 2016/09/15 16:53:18]

We need to actually do this to match spec; navigator.presentation.receiver must
be null in a non-receiving browsing context.

http://w3c.github.io/presentation-api/#receiving-user-agent

Can you replace TODO(mlamouri) here with TODO(crbug.com/647296) here?

[zhaobin, 2016/09/15 18:56:03]

Done.

     if (!m_receiver)
-        m_receiver = new PresentationReceiver(frame());
+        m_receiver = new PresentationReceiver(frame(), client);
     return m_receiver;
 }
 
 } // namespace blink