Preparations for Cast Host Extension

remoting/host/client_session.cc

 // Copyright (c) 2012 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 "remoting/host/client_session.h"
 
 #include <algorithm>
 
 #include "base/message_loop/message_loop_proxy.h"
 #include "remoting/base/capabilities.h"
@@ skipping 49 matching lines @@
       auth_input_filter_(&disable_input_filter_),
       auth_clipboard_filter_(&disable_clipboard_filter_),
       client_clipboard_factory_(clipboard_echo_filter_.client_filter()),
       max_duration_(max_duration),
       audio_task_runner_(audio_task_runner),
       input_task_runner_(input_task_runner),
       video_capture_task_runner_(video_capture_task_runner),
       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
   // set before channels are connected. Make it possible to set stubs
   // later and set them only when connection is authenticated.
   connection_->set_clipboard_stub(&auth_clipboard_filter_);
   connection_->set_host_stub(this);
   connection_->set_input_stub(&auth_input_filter_);
 
   // |auth_*_filter_|'s states reflect whether the session is authenticated.
@@ skipping 230 matching lines @@
   input_injector_ = desktop_environment_->CreateInputInjector();
 
   // Connect the host clipboard and input stubs.
   host_input_filter_.set_input_stub(input_injector_.get());
   clipboard_echo_filter_.set_host_stub(input_injector_.get());
 
   // Create a VideoEncoder based on the session's video channel configuration.
   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_,
       network_task_runner_,
       desktop_environment_->CreateVideoCapturer(),
       video_encoder.Pass(),
       connection_->client_stub(),
       &mouse_clamping_filter_);
 
   // Create an AudioScheduler if audio is enabled, to pump audio samples.
@@ skipping 142 matching lines @@
 
 scoped_ptr<protocol::ClipboardStub> ClientSession::CreateClipboardProxy() {
   DCHECK(CalledOnValidThread());
 
   return scoped_ptr<protocol::ClipboardStub>(
       new protocol::ClipboardThreadProxy(
           client_clipboard_factory_.GetWeakPtr(),
           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(
     const protocol::SessionConfig& config) {
   const protocol::ChannelConfig& video_config = config.video_config();
 
   if (video_config.codec == protocol::ChannelConfig::CODEC_VP8) {
     return remoting::VideoEncoderVpx::CreateForVP8().PassAs<VideoEncoder>();
   } else if (video_config.codec == protocol::ChannelConfig::CODEC_VP9) {
     return remoting::VideoEncoderVpx::CreateForVP9().PassAs<VideoEncoder>();
@@ skipping 12 matching lines @@
     return scoped_ptr<AudioEncoder>(new AudioEncoderVerbatim());
   } else if (audio_config.codec == protocol::ChannelConfig::CODEC_OPUS) {
     return scoped_ptr<AudioEncoder>(new AudioEncoderOpus());
   }
 
   NOTREACHED();
   return scoped_ptr<AudioEncoder>();
 }
 
 }  // namespace remoting