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

content/renderer/presentation/presentation_dispatcher.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/renderer/presentation/presentation_dispatcher.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 63 matching lines @@
   }
 }
 
 }  // namespace
 
 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
   // destroyed.
   DCHECK(!controller_);
 }
 
 void PresentationDispatcher::setController(
     blink::WebPresentationController* controller) {
   // There shouldn't be any swapping from one non-null controller to another.
@@ skipping 291 matching lines @@
   if (!error.is_null()) {
     DCHECK(session_info.is_null());
     callback->onError(blink::WebPresentationError(
         GetWebPresentationErrorTypeFromMojo(error->error_type),
         blink::WebString::fromUTF8(error->message)));
     return;
   }
 
   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(
     blink::mojom::PresentationSessionInfoPtr connection,
     blink::mojom::PresentationConnectionState state) {
   if (!controller_)
     return;
 
   DCHECK(!connection.is_null());
   controller_->didChangeSessionState(
@@ skipping 126 matching lines @@
 PresentationDispatcher::AvailabilityStatus::AvailabilityStatus(
     const GURL& availability_url)
     : url(availability_url),
       last_known_availability(false),
       listening_state(ListeningState::INACTIVE) {}
 
 PresentationDispatcher::AvailabilityStatus::~AvailabilityStatus() {
 }
 
 }  // namespace content