Preparations for Cast Host Extension

remoting/host/client_session.cc

Index: remoting/host/client_session.cc
diff --git a/remoting/host/client_session.cc b/remoting/host/client_session.cc
index 55e4decc1ca3bb70e29df4836cd787e0f1fbed1c..b0c72bbde60f1b4565eca55e170036ff739a60ec 100644
--- a/remoting/host/client_session.cc
+++ b/remoting/host/client_session.cc
@@ -67,7 +67,8 @@ ClientSession::ClientSession(
       video_encode_task_runner_(video_encode_task_runner),
       network_task_runner_(network_task_runner),
       ui_task_runner_(ui_task_runner),
-      pairing_registry_(pairing_registry) {
+      pairing_registry_(pairing_registry),
+      enable_cast_(false) {
   connection_->SetEventHandler(this);
 
   // TODO(sergeyu): Currently ConnectionToClient expects stubs to be
@@ -318,7 +319,6 @@ void ClientSession::OnConnectionAuthenticated(
   scoped_ptr<VideoEncoder> video_encoder =
       CreateVideoEncoder(connection_->session()->config());
 
-  // Create a VideoScheduler to pump frames from the capturer to the client.
   video_scheduler_ = new VideoScheduler(
       video_capture_task_runner_,
       video_encode_task_runner_,
@@ -481,6 +481,26 @@ scoped_ptr<protocol::ClipboardStub> ClientSession::CreateClipboardProxy() {
           base::MessageLoopProxy::current()));
 }
 
+scoped_ptr<webrtc::ScreenCapturer> ClientSession::RequestScreenCapturer() {
+  // VideoScheduler must be stopped on one of these threads.
+  DCHECK(video_capture_task_runner_->BelongsToCurrentThread() ||
+         network_task_runner_->BelongsToCurrentThread());
+
+  if(!enable_cast_) {

[Sergey Ulanov, 2014/07/24 19:11:36]

I still think you don't need this flag. RequestScreenCapturer() will only be
called from extension and extension shouldn't exist if cast is not enabled.

[aiguha, 2014/07/28 17:11:56]

Acknowledged.

+    LOG(ERROR) << "Cast mode not enabled.";
+    return scoped_ptr<webrtc::ScreenCapturer>();
+  }
+
+  if (!video_scheduler_.get()) {
+    LOG(ERROR) << "Video Scheduler was NULL, but shouldn't have been.";
+    return scoped_ptr<webrtc::ScreenCapturer>();
+  }
+
+  video_scheduler_->Stop();
+
+  return desktop_environment_->CreateVideoCapturer();

[aiguha, 2014/07/18 21:30:37]

As of now, this method is called on the network thread. Calling
video_scheduler_->Stop() here triggers the deletion of the old ScreenCapturer on
the capture thread. We then createand return a new ScreenCapturer immediately
after. 
This works in practice (on Linux atleast), but could there be a race condition
between deletion and creation? Or is there no such constraint on Linux?

+}
+
 // TODO(sergeyu): Move this to SessionManager?
 // static
 scoped_ptr<VideoEncoder> ClientSession::CreateVideoEncoder(