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

content/renderer/presentation/presentation_dispatcher.cc

Index: content/renderer/presentation/presentation_dispatcher.cc
diff --git a/content/renderer/presentation/presentation_dispatcher.cc b/content/renderer/presentation/presentation_dispatcher.cc
index a0b3125568cfa47217c6424ab470549d34f99c92..321acb43d4a72a53fa5c6fcb65d4b1d3a45260ba 100644
--- a/content/renderer/presentation/presentation_dispatcher.cc
+++ b/content/renderer/presentation/presentation_dispatcher.cc
@@ -81,8 +81,8 @@ namespace content {
 PresentationDispatcher::PresentationDispatcher(RenderFrame* render_frame)
     : RenderFrameObserver(render_frame),
       controller_(nullptr),
-      binding_(this) {
-}
+      receiver_(nullptr),
+      binding_(this) {}
 
 PresentationDispatcher::~PresentationDispatcher() {
   // Controller should be destroyed before the dispatcher when frame is
@@ -394,16 +394,35 @@ void PresentationDispatcher::OnSessionCreated(
 
   DCHECK(!session_info.is_null());
   presentation_service_->ListenForSessionMessages(session_info.Clone());
-  callback->onSuccess(
-      base::MakeUnique<PresentationConnectionClient>(std::move(session_info)));
+
+  RendererPresentationConnection* controller_connection_proxy =

[mark a. foltz, 2016/10/10 18:28:52]

How do you know this connection is for an offscreen presentation?

I think you'll need to add something in |session_info| to know whether to pass
the connection to the OffscreenPresentationManager.

[zhaobin, 2016/10/12 02:27:33]

Done.

+      new RendererPresentationConnection();
+  // Bind controller_connection_proxy with PresentationConnection
+  // in controller page.
+  callback->onSuccess(base::MakeUnique<PresentationConnectionClient>(

[imcheng, 2016/10/12 02:22:55]

It looks like we don't need the 2-argument PresentationConnectionClient
constructor. What we are doing here (and in OnReceiverConnectionAvailable) is
create a RendererPresentationConnection, perform some operation on it, then pass
its ownership to PresentationConnectionClient. Another way is:
- create PresentationConnectionClient
- ask it to instantiate a RendererPresentationConnection and return a raw
pointer (non-ownership) to it (createProxy)
- perform operation on the RendererPresentationConnection.

[zhaobin, 2016/10/13 02:33:52]

Did some changes in new patch so we use 2-argument constructor for 1-UA mode;
and original constructors for other connections.

+      session_info.Clone(), controller_connection_proxy));
+
+  // Pass controller_connection_proxy to PSImpl and register
+  // it with OffscreenPresentationManager.
+  presentation_service_->SetPresentationConnection(
+      session_info.Clone(), controller_connection_proxy->Bind());

[imcheng, 2016/10/12 02:22:54]

|controller_connection_proxy| might have already been deleted at this point:

- PresentationConnectionClient, which is passed into the callback, takes
ownership of it
- The proxy object might be released before the callback returns, see:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/presen...
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/presen...

[zhaobin, 2016/10/13 02:33:52]

Done.

 }
 
 void PresentationDispatcher::OnReceiverConnectionAvailable(
-    blink::mojom::PresentationSessionInfoPtr session_info) {
-  if (receiver_) {
-    receiver_->onReceiverConnectionAvailable(
-        new PresentationConnectionClient(std::move(session_info)));
-  }
+    blink::mojom::PresentationSessionInfoPtr session_info,
+    blink::mojom::PresentationConnectionPtr controller) {
+  if (!receiver_)
+    return;
+
+  RendererPresentationConnection* receiver_connection_proxy =
+      new RendererPresentationConnection();
+  // Bind receiver_connection_proxy with PresentationConnection
+  // in receiver page.
+  receiver_->onReceiverConnectionAvailable(new PresentationConnectionClient(
+      std::move(session_info), receiver_connection_proxy));
+
+  controller->SetTargetConnection(receiver_connection_proxy->Bind());
+  receiver_connection_proxy->SetTargetConnection(std::move(controller));
 }
 
 void PresentationDispatcher::OnConnectionStateChanged(