Cast: Don't create threads for each CastSessionDelegate

We shouldn't create threads for each instance of CastSessionDelegate.

Cast encoding threads are now managed by a singleton object of
CastThreads. Threads used by Cast are now started and stopped
accordingly when there are CastSessionDelegate objects.

Tested with browser_tests --gtest_filter=CastStreaming*

BUG=317006

Review URL: https://codereview.chromium.org/174403002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252810 0039d316-1c4b-4281-b951-d872f2087c98

chrome/chrome_renderer.gypi

@@ -169,6 +169,8 @@
         'renderer/media/cast_session.h',
         'renderer/media/cast_session_delegate.cc',
         'renderer/media/cast_session_delegate.h',
+        'renderer/media/cast_threads.cc',
+        'renderer/media/cast_threads.h',
         'renderer/media/cast_transport_sender_ipc.cc',
         'renderer/media/cast_transport_sender_ipc.h',
         'renderer/media/cast_udp_transport.cc',

chrome/renderer/media/cast_session_delegate.cc

@@ -4,8 +4,10 @@
 
 #include "chrome/renderer/media/cast_session_delegate.h"
 
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "chrome/renderer/media/cast_threads.h"
 #include "chrome/renderer/media/cast_transport_sender_ipc.h"
 #include "content/public/renderer/p2p_socket_client.h"
 #include "content/public/renderer/render_thread.h"
@@ -21,10 +23,11 @@ using media::cast::CastEnvironment;
 using media::cast::CastSender;
 using media::cast::VideoSenderConfig;
 
+static base::LazyInstance<CastThreads> g_cast_threads =
+    LAZY_INSTANCE_INITIALIZER;
+
 CastSessionDelegate::CastSessionDelegate()
-    : audio_encode_thread_("CastAudioEncodeThread"),
-      video_encode_thread_("CastVideoEncodeThread"),
-      transport_configured_(false),
+    : transport_configured_(false),
       io_message_loop_proxy_(
           content::RenderThread::Get()->GetIOMessageLoopProxy()) {
   DCHECK(io_message_loop_proxy_);
@@ -38,9 +41,6 @@ void CastSessionDelegate::Initialize() {
   if (cast_environment_)
     return;  // Already initialized.
 
-  audio_encode_thread_.Start();
-  video_encode_thread_.Start();
-
   // CastSender uses the renderer's IO thread as the main thread. This reduces
   // thread hopping for incoming video frames and outgoing network packets.
   // There's no need to decode so no thread assigned for decoding.
@@ -48,9 +48,9 @@ void CastSessionDelegate::Initialize() {
   cast_environment_ = new CastEnvironment(
       scoped_ptr<base::TickClock>(new base::DefaultTickClock()).Pass(),
       base::MessageLoopProxy::current(),
-      audio_encode_thread_.message_loop_proxy(),
+      g_cast_threads.Get().GetAudioEncodeMessageLoopProxy(),
       NULL,
-      video_encode_thread_.message_loop_proxy(),
+      g_cast_threads.Get().GetVideoEncodeMessageLoopProxy(),
       NULL,
       base::MessageLoopProxy::current(),
       media::cast::GetDefaultCastSenderLoggingConfig());

chrome/renderer/media/cast_session_delegate.h

@@ -78,13 +78,6 @@ class CastSessionDelegate {
   scoped_ptr<media::cast::CastSender> cast_sender_;
   scoped_ptr<media::cast::transport::CastTransportSender> cast_transport_;
 
-  // Utilities threads owned by this class. They are used by CastSender for
-  // encoding.
-  // TODO(hclam): See crbug.com/317006 for more details.
-  // This class shouldn't create and own threads.
-  base::Thread audio_encode_thread_;
-  base::Thread video_encode_thread_;
-
   // Configuration for audio and video.
   scoped_ptr<media::cast::AudioSenderConfig> audio_config_;
   scoped_ptr<media::cast::VideoSenderConfig> video_config_;

chrome/renderer/media/cast_threads.cc

+// 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 "chrome/renderer/media/cast_threads.h"
+
+#include "base/logging.h"
+
+CastThreads::CastThreads()
+    : audio_encode_thread_("CastAudioEncodeThread"),
+      video_encode_thread_("CastVideoEncodeThread") {
+  audio_encode_thread_.Start();
+  video_encode_thread_.Start();
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
+CastThreads::GetAudioEncodeMessageLoopProxy() {
+  return audio_encode_thread_.message_loop_proxy();
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
+CastThreads::GetVideoEncodeMessageLoopProxy() {
+  return video_encode_thread_.message_loop_proxy();
+}

chrome/renderer/media/cast_threads.h

+// 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.
+
+// Manages threads used by Cast Streaming Extensions API. There is a
+// singleton object of this class in the renderer.
+//
+// There are two threads owned by this class:
+// 1. Audio encode thread.
+// 2. Video encode thread.
+// These two threads are started this object is created.
+
+#ifndef CHROME_RENDERER_MEDIA_CAST_THREADS_H_
+#define CHROME_RENDERER_MEDIA_CAST_THREADS_H_
+
+#include "base/lazy_instance.h"
+#include "base/threading/thread.h"
+
+class CastThreads {
+ public:
+  scoped_refptr<base::SingleThreadTaskRunner>
+  GetAudioEncodeMessageLoopProxy();
+  scoped_refptr<base::SingleThreadTaskRunner>
+  GetVideoEncodeMessageLoopProxy();
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<CastThreads>;
+
+  CastThreads();
+
+  base::Thread audio_encode_thread_;
+  base::Thread video_encode_thread_;
+
+  DISALLOW_COPY_AND_ASSIGN(CastThreads);
+};
+
+#endif  // CHROME_RENDERER_MEDIA_CAST_THREADS_H_