Cast:Switching to SingleThreadTaskRunner

BUG= 337558

Review URL: https://codereview.chromium.org/151663002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249044 0039d316-1c4b-4281-b951-d872f2087c98

37 files changed, 192 insertions, 164 deletions

diff --git a/media/cast/audio_receiver/audio_decoder_unittest.cc b/media/cast/audio_receiver/audio_decoder_unittest.cc
index 962217d..703d733 100644
--- a/media/cast/audio_receiver/audio_decoder_unittest.cc
+++ b/media/cast/audio_receiver/audio_decoder_unittest.cc
@@ -5,7 +5,7 @@
 #include "base/test/simple_test_tick_clock.h"
 #include "media/cast/audio_receiver/audio_decoder.h"
 #include "media/cast/cast_environment.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 namespace media {
@@ -29,7 +29,7 @@ class AudioDecoderTest : public ::testing::Test {
   AudioDecoderTest() {
     testing_clock_ = new base::SimpleTestTickClock();
     testing_clock_->Advance(base::TimeDelta::FromMilliseconds(1234));
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ =
         new CastEnvironment(scoped_ptr<base::TickClock>(testing_clock_).Pass(),
                             task_runner_,
@@ -50,7 +50,7 @@ class AudioDecoderTest : public ::testing::Test {
   TestRtpPayloadFeedback cast_feedback_;
   // Owned by CastEnvironment.
   base::SimpleTestTickClock* testing_clock_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   scoped_ptr<AudioDecoder> audio_decoder_;
 
diff --git a/media/cast/audio_receiver/audio_receiver_unittest.cc b/media/cast/audio_receiver/audio_receiver_unittest.cc
index d1f1464..9aaa9fd 100644
--- a/media/cast/audio_receiver/audio_receiver_unittest.cc
+++ b/media/cast/audio_receiver/audio_receiver_unittest.cc
@@ -10,7 +10,7 @@
 #include "media/cast/cast_defines.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/rtcp/test_rtcp_packet_builder.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/pacing/mock_paced_packet_sender.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -79,7 +79,7 @@ class AudioReceiverTest : public ::testing::Test {
     testing_clock_ = new base::SimpleTestTickClock();
     testing_clock_->Advance(
         base::TimeDelta::FromMilliseconds(kStartMillisecond));
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ =
         new CastEnvironment(scoped_ptr<base::TickClock>(testing_clock_).Pass(),
                             task_runner_,
@@ -118,7 +118,7 @@ class AudioReceiverTest : public ::testing::Test {
   RtpCastHeader rtp_header_;
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
   transport::MockPacedPacketSender mock_transport_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<PeerAudioReceiver> receiver_;
   scoped_refptr<CastEnvironment> cast_environment_;
   scoped_refptr<TestAudioEncoderCallback> test_audio_encoder_callback_;
diff --git a/media/cast/audio_sender/audio_encoder_unittest.cc b/media/cast/audio_sender/audio_encoder_unittest.cc
index 09f0697..72a8c4e 100644
--- a/media/cast/audio_sender/audio_encoder_unittest.cc
+++ b/media/cast/audio_sender/audio_encoder_unittest.cc
@@ -13,7 +13,7 @@
 #include "media/cast/audio_sender/audio_encoder.h"
 #include "media/cast/cast_config.h"
 #include "media/cast/cast_environment.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/test/utility/audio_utility.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -90,7 +90,7 @@ class AudioEncoderTest : public ::testing::TestWithParam<TestScenario> {
   }
 
   virtual void SetUp() {
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ =
         new CastEnvironment(scoped_ptr<base::TickClock>(testing_clock_).Pass(),
                             task_runner_,
@@ -166,7 +166,7 @@ class AudioEncoderTest : public ::testing::TestWithParam<TestScenario> {
   void IncrementReleaseCallbackCounter() { ++release_callback_count_; }
 
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<TestAudioBusFactory> audio_bus_factory_;
   scoped_ptr<TestEncodedAudioFrameReceiver> receiver_;
   scoped_refptr<AudioEncoder> audio_encoder_;
diff --git a/media/cast/audio_sender/audio_sender_unittest.cc b/media/cast/audio_sender/audio_sender_unittest.cc
index 1215e3c..dc2c3bf 100644
--- a/media/cast/audio_sender/audio_sender_unittest.cc
+++ b/media/cast/audio_sender/audio_sender_unittest.cc
@@ -11,7 +11,7 @@
 #include "media/cast/cast_config.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/rtcp/rtcp.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/test/utility/audio_utility.h"
 #include "media/cast/transport/cast_transport_config.h"
 #include "media/cast/transport/cast_transport_sender_impl.h"
@@ -60,7 +60,7 @@ class AudioSenderTest : public ::testing::Test {
     testing_clock_ = new base::SimpleTestTickClock();
     testing_clock_->Advance(
         base::TimeDelta::FromMilliseconds(kStartMillisecond));
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ =
         new CastEnvironment(scoped_ptr<base::TickClock>(testing_clock_).Pass(),
                             task_runner_,
@@ -100,7 +100,7 @@ class AudioSenderTest : public ::testing::Test {
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
   TestPacketSender transport_;
   scoped_ptr<transport::CastTransportSenderImpl> transport_sender_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<AudioSender> audio_sender_;
   scoped_refptr<CastEnvironment> cast_environment_;
   AudioSenderConfig audio_config_;
diff --git a/media/cast/cast.gyp b/media/cast/cast.gyp
index ac90b7c..feaa1a2 100644
--- a/media/cast/cast.gyp
+++ b/media/cast/cast.gyp
@@ -84,8 +84,8 @@
             'test/end2end_unittest.cc',
             'test/fake_gpu_video_accelerator_factories.cc',
             'test/fake_gpu_video_accelerator_factories.h',
-            'test/fake_task_runner.cc',
-            'test/fake_task_runner.h',
+            'test/fake_single_thread_task_runner.cc',
+            'test/fake_single_thread_task_runner.h',
             'test/fake_video_encode_accelerator.cc',
             'test/fake_video_encode_accelerator.h',
             'transport/pacing/mock_paced_packet_sender.cc',
diff --git a/media/cast/cast_environment.cc b/media/cast/cast_environment.cc
index 2284adb..8efd6e6 100644
--- a/media/cast/cast_environment.cc
+++ b/media/cast/cast_environment.cc
@@ -8,7 +8,7 @@
 #include "base/location.h"
 #include "base/logging.h"
 
-using base::TaskRunner;
+using base::SingleThreadTaskRunner;
 
 namespace {
 
@@ -23,12 +23,12 @@ namespace cast {
 
 CastEnvironment::CastEnvironment(
     scoped_ptr<base::TickClock> clock,
-    scoped_refptr<TaskRunner> main_thread_proxy,
-    scoped_refptr<TaskRunner> audio_encode_thread_proxy,
-    scoped_refptr<TaskRunner> audio_decode_thread_proxy,
-    scoped_refptr<TaskRunner> video_encode_thread_proxy,
-    scoped_refptr<TaskRunner> video_decode_thread_proxy,
-    scoped_refptr<TaskRunner> transport_thread_proxy,
+    scoped_refptr<SingleThreadTaskRunner> main_thread_proxy,
+    scoped_refptr<SingleThreadTaskRunner> audio_encode_thread_proxy,
+    scoped_refptr<SingleThreadTaskRunner> audio_decode_thread_proxy,
+    scoped_refptr<SingleThreadTaskRunner> video_encode_thread_proxy,
+    scoped_refptr<SingleThreadTaskRunner> video_decode_thread_proxy,
+    scoped_refptr<SingleThreadTaskRunner> transport_thread_proxy,
     const CastLoggingConfig& config)
     : clock_(clock.Pass()),
       main_thread_proxy_(main_thread_proxy),
@@ -55,8 +55,8 @@ CastEnvironment::~CastEnvironment() {
 bool CastEnvironment::PostTask(ThreadId identifier,
                                const tracked_objects::Location& from_here,
                                const base::Closure& task) {
-  scoped_refptr<TaskRunner> task_runner =
-      GetMessageTaskRunnerForThread(identifier);
+  scoped_refptr<SingleThreadTaskRunner> task_runner =
+      GetMessageSingleThreadTaskRunnerForThread(identifier);
 
   return task_runner->PostTask(from_here, task);
 }
@@ -65,13 +65,14 @@ bool CastEnvironment::PostDelayedTask(ThreadId identifier,
                                  const tracked_objects::Location& from_here,
                                  const base::Closure& task,
                                  base::TimeDelta delay) {
-  scoped_refptr<TaskRunner> task_runner =
-      GetMessageTaskRunnerForThread(identifier);
+  scoped_refptr<SingleThreadTaskRunner> task_runner =
+      GetMessageSingleThreadTaskRunnerForThread(identifier);
 
   return task_runner->PostDelayedTask(from_here, task, delay);
 }
 
-scoped_refptr<TaskRunner> CastEnvironment::GetMessageTaskRunnerForThread(
+scoped_refptr<SingleThreadTaskRunner>
+CastEnvironment::GetMessageSingleThreadTaskRunnerForThread(
     ThreadId identifier) {
   switch (identifier) {
     case CastEnvironment::MAIN:
diff --git a/media/cast/cast_environment.h b/media/cast/cast_environment.h
index 5c6df6f..5abb5c7 100644
--- a/media/cast/cast_environment.h
+++ b/media/cast/cast_environment.h
@@ -8,7 +8,7 @@
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "media/cast/logging/logging_defines.h"
@@ -34,18 +34,19 @@ class CastEnvironment : public base::RefCountedThreadSafe<CastEnvironment> {
     VIDEO_ENCODER,
     // The video decoder thread is where the video decode processing is done.
     VIDEO_DECODER,
-     // The transport thread is where the transport processing is done.
+    // The transport thread is where the transport processing is done.
     TRANSPORT,
   };
 
-  CastEnvironment(scoped_ptr<base::TickClock> clock,
-                  scoped_refptr<base::TaskRunner> main_thread_proxy,
-                  scoped_refptr<base::TaskRunner> audio_encode_thread_proxy,
-                  scoped_refptr<base::TaskRunner> audio_decode_thread_proxy,
-                  scoped_refptr<base::TaskRunner> video_encode_thread_proxy,
-                  scoped_refptr<base::TaskRunner> video_decode_thread_proxy,
-                  scoped_refptr<base::TaskRunner> transport_thread_proxy,
-                  const CastLoggingConfig& config);
+  CastEnvironment(
+      scoped_ptr<base::TickClock> clock,
+      scoped_refptr<base::SingleThreadTaskRunner> main_thread_proxy,
+      scoped_refptr<base::SingleThreadTaskRunner> audio_encode_thread_proxy,
+      scoped_refptr<base::SingleThreadTaskRunner> audio_decode_thread_proxy,
+      scoped_refptr<base::SingleThreadTaskRunner> video_encode_thread_proxy,
+      scoped_refptr<base::SingleThreadTaskRunner> video_decode_thread_proxy,
+      scoped_refptr<base::SingleThreadTaskRunner> transport_thread_proxy,
+      const CastLoggingConfig& config);
 
   // These are the same methods in message_loop.h, but are guaranteed to either
   // get posted to the MessageLoop if it's still alive, or be deleted otherwise.
@@ -68,8 +69,8 @@ class CastEnvironment : public base::RefCountedThreadSafe<CastEnvironment> {
   // Logging is not thread safe. Should always be called from the main thread.
   LoggingImpl* Logging();
 
-  scoped_refptr<base::TaskRunner> GetMessageTaskRunnerForThread(
-      ThreadId identifier);
+  scoped_refptr<base::SingleThreadTaskRunner>
+      GetMessageSingleThreadTaskRunnerForThread(ThreadId identifier);
 
   bool HasAudioEncoderThread() {
     return audio_encode_thread_proxy_ ? true : false;
@@ -86,12 +87,12 @@ class CastEnvironment : public base::RefCountedThreadSafe<CastEnvironment> {
   friend class base::RefCountedThreadSafe<CastEnvironment>;
 
   scoped_ptr<base::TickClock> clock_;
-  scoped_refptr<base::TaskRunner> main_thread_proxy_;
-  scoped_refptr<base::TaskRunner> audio_encode_thread_proxy_;
-  scoped_refptr<base::TaskRunner> audio_decode_thread_proxy_;
-  scoped_refptr<base::TaskRunner> video_encode_thread_proxy_;
-  scoped_refptr<base::TaskRunner> video_decode_thread_proxy_;
-  scoped_refptr<base::TaskRunner> transport_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> main_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> audio_encode_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> audio_decode_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> video_encode_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> video_decode_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> transport_thread_proxy_;
 
   scoped_ptr<LoggingImpl> logging_;
 
diff --git a/media/cast/cast_receiver_impl.cc b/media/cast/cast_receiver_impl.cc
index 75b0032..33b13c3 100644
--- a/media/cast/cast_receiver_impl.cc
+++ b/media/cast/cast_receiver_impl.cc
@@ -90,7 +90,7 @@ CastReceiverImpl::CastReceiverImpl(
     transport::PacketSender* const packet_sender)
     : pacer_(cast_environment->Clock(),
              packet_sender,
-             cast_environment->GetMessageTaskRunnerForThread(
+             cast_environment->GetMessageSingleThreadTaskRunnerForThread(
                  CastEnvironment::TRANSPORT)),
       audio_receiver_(cast_environment, audio_config, &pacer_),
       video_receiver_(cast_environment, video_config, &pacer_),
diff --git a/media/cast/logging/logging_impl.cc b/media/cast/logging/logging_impl.cc
index 90af985..7b5ff4b 100644
--- a/media/cast/logging/logging_impl.cc
+++ b/media/cast/logging/logging_impl.cc
@@ -10,8 +10,9 @@
 namespace media {
 namespace cast {
 
-LoggingImpl::LoggingImpl(scoped_refptr<base::TaskRunner> main_thread_proxy,
-                         const CastLoggingConfig& config)
+LoggingImpl::LoggingImpl(
+    scoped_refptr<base::SingleThreadTaskRunner> main_thread_proxy,
+    const CastLoggingConfig& config)
     : main_thread_proxy_(main_thread_proxy),
       config_(config),
       raw_(config.is_sender),
diff --git a/media/cast/logging/logging_impl.h b/media/cast/logging/logging_impl.h
index bf51869..a0e1ed9 100644
--- a/media/cast/logging/logging_impl.h
+++ b/media/cast/logging/logging_impl.h
@@ -11,7 +11,7 @@
 // 3. Tracing of raw events.
 
 #include "base/memory/ref_counted.h"
-#include "base/task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "media/cast/cast_config.h"
 #include "media/cast/logging/logging_defines.h"
 #include "media/cast/logging/logging_raw.h"
@@ -23,7 +23,7 @@ namespace cast {
 // Should only be called from the main thread.
 class LoggingImpl : public base::NonThreadSafe {
  public:
-  LoggingImpl(scoped_refptr<base::TaskRunner> main_thread_proxy,
+  LoggingImpl(scoped_refptr<base::SingleThreadTaskRunner> main_thread_proxy,
               const CastLoggingConfig& config);
 
   ~LoggingImpl();
@@ -80,7 +80,7 @@ class LoggingImpl : public base::NonThreadSafe {
 
  private:
   void InsertGenericUmaEvent(CastLoggingEvent event, int value);
-  scoped_refptr<base::TaskRunner> main_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> main_thread_proxy_;
   const CastLoggingConfig config_;
   LoggingRaw raw_;
   LoggingStats stats_;
diff --git a/media/cast/logging/logging_unittest.cc b/media/cast/logging/logging_unittest.cc
index 75915de..c07571b 100644
--- a/media/cast/logging/logging_unittest.cc
+++ b/media/cast/logging/logging_unittest.cc
@@ -9,7 +9,7 @@
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "media/cast/logging/logging_impl.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 
 namespace media {
 namespace cast {
@@ -32,14 +32,14 @@ class TestLogging : public ::testing::Test {
 
     testing_clock_.Advance(
         base::TimeDelta::FromMilliseconds(kStartMillisecond));
-    task_runner_ = new test::FakeTaskRunner(&testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(&testing_clock_);
     logging_.reset(new LoggingImpl(task_runner_, config_));
   }
 
   virtual ~TestLogging() {}
 
   CastLoggingConfig config_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<LoggingImpl> logging_;
   base::SimpleTestTickClock testing_clock_;
 };
diff --git a/media/cast/rtcp/rtcp_receiver_unittest.cc b/media/cast/rtcp/rtcp_receiver_unittest.cc
index 78a3dba..3afb340 100644
--- a/media/cast/rtcp/rtcp_receiver_unittest.cc
+++ b/media/cast/rtcp/rtcp_receiver_unittest.cc
@@ -10,7 +10,7 @@
 #include "media/cast/rtcp/rtcp_receiver.h"
 #include "media/cast/rtcp/rtcp_utility.h"
 #include "media/cast/rtcp/test_rtcp_packet_builder.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/cast_transport_defines.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -156,7 +156,7 @@ class RtcpReceiverTest : public ::testing::Test {
  protected:
   RtcpReceiverTest()
       : testing_clock_(new base::SimpleTestTickClock()),
-        task_runner_(new test::FakeTaskRunner(testing_clock_)),
+        task_runner_(new test::FakeSingleThreadTaskRunner(testing_clock_)),
         cast_environment_(new CastEnvironment(
             scoped_ptr<base::TickClock>(testing_clock_).Pass(),
             task_runner_,
@@ -208,7 +208,7 @@ class RtcpReceiverTest : public ::testing::Test {
   }
 
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   MockRtcpReceiverFeedback mock_receiver_feedback_;
   MockRtcpRttFeedback mock_rtt_feedback_;
diff --git a/media/cast/rtcp/rtcp_sender_unittest.cc b/media/cast/rtcp/rtcp_sender_unittest.cc
index f6d491c..c626eb9 100644
--- a/media/cast/rtcp/rtcp_sender_unittest.cc
+++ b/media/cast/rtcp/rtcp_sender_unittest.cc
@@ -9,7 +9,7 @@
 #include "media/cast/rtcp/rtcp_sender.h"
 #include "media/cast/rtcp/rtcp_utility.h"
 #include "media/cast/rtcp/test_rtcp_packet_builder.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/cast_transport_defines.h"
 #include "media/cast/transport/pacing/paced_sender.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -57,7 +57,7 @@ class RtcpSenderTest : public ::testing::Test {
  protected:
   RtcpSenderTest()
       : testing_clock_(new base::SimpleTestTickClock()),
-        task_runner_(new test::FakeTaskRunner(testing_clock_)),
+        task_runner_(new test::FakeSingleThreadTaskRunner(testing_clock_)),
         cast_environment_(new CastEnvironment(
             scoped_ptr<base::TickClock>(testing_clock_).Pass(),
             task_runner_,
@@ -74,7 +74,7 @@ class RtcpSenderTest : public ::testing::Test {
 
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
   TestRtcpTransport test_transport_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   scoped_ptr<RtcpSender> rtcp_sender_;
 
diff --git a/media/cast/rtcp/rtcp_unittest.cc b/media/cast/rtcp/rtcp_unittest.cc
index a762982..cf74ef5 100644
--- a/media/cast/rtcp/rtcp_unittest.cc
+++ b/media/cast/rtcp/rtcp_unittest.cc
@@ -9,7 +9,7 @@
 #include "media/cast/rtcp/mock_rtcp_sender_feedback.h"
 #include "media/cast/rtcp/rtcp.h"
 #include "media/cast/rtcp/test_rtcp_packet_builder.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/cast_transport_config.h"
 #include "media/cast/transport/cast_transport_sender_impl.h"
 #include "media/cast/transport/pacing/paced_sender.h"
@@ -144,7 +144,7 @@ class RtcpTest : public ::testing::Test {
  protected:
   RtcpTest()
       : testing_clock_(new base::SimpleTestTickClock()),
-        task_runner_(new test::FakeTaskRunner(testing_clock_)),
+        task_runner_(new test::FakeSingleThreadTaskRunner(testing_clock_)),
         cast_environment_(new CastEnvironment(
             scoped_ptr<base::TickClock>(testing_clock_).Pass(),
             task_runner_,
@@ -183,7 +183,7 @@ class RtcpTest : public ::testing::Test {
   }
 
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   RtcpTestPacketSender sender_to_receiver_;
   scoped_ptr<transport::CastTransportSenderImpl> transport_sender_;
diff --git a/media/cast/test/encode_decode_test.cc b/media/cast/test/encode_decode_test.cc
index ddae972..a405242 100644
--- a/media/cast/test/encode_decode_test.cc
+++ b/media/cast/test/encode_decode_test.cc
@@ -12,7 +12,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "media/base/video_frame.h"
 #include "media/cast/cast_environment.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/test/utility/video_utility.h"
 #include "media/cast/video_receiver/codecs/vp8/vp8_decoder.h"
 #include "media/cast/video_sender/codecs/vp8/vp8_encoder.h"
@@ -71,7 +71,7 @@ class EncodeDecodeTest : public ::testing::Test {
  protected:
   EncodeDecodeTest()
       : testing_clock_(new base::SimpleTestTickClock()),
-        task_runner_(new test::FakeTaskRunner(testing_clock_)),
+        task_runner_(new test::FakeSingleThreadTaskRunner(testing_clock_)),
         // CastEnvironment will only be used by the vp8 decoder; Enable only the
         // video decoder and main threads.
         cast_environment_(new CastEnvironment(
@@ -117,7 +117,7 @@ class EncodeDecodeTest : public ::testing::Test {
   scoped_ptr<Vp8Decoder> decoder_;
   scoped_refptr<media::VideoFrame> video_frame_;
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   scoped_refptr<EncodeDecodeTestFrameCallback> test_callback_;
 };
diff --git a/media/cast/test/end2end_unittest.cc b/media/cast/test/end2end_unittest.cc
index f85ab59..ec2560a 100644
--- a/media/cast/test/end2end_unittest.cc
+++ b/media/cast/test/end2end_unittest.cc
@@ -23,7 +23,7 @@
 #include "media/cast/cast_environment.h"
 #include "media/cast/cast_receiver.h"
 #include "media/cast/cast_sender.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/test/utility/audio_utility.h"
 #include "media/cast/test/utility/video_utility.h"
 #include "media/cast/transport/cast_transport_config.h"
@@ -335,8 +335,9 @@ class End2EndTest : public ::testing::Test {
   End2EndTest()
       : start_time_(),
         testing_clock_(new base::SimpleTestTickClock()),
-        task_runner_(new test::FakeTaskRunner(testing_clock_)),
-        transport_task_runner_(new test::FakeTaskRunner(testing_clock_)),
+        task_runner_(new test::FakeSingleThreadTaskRunner(testing_clock_)),
+        transport_task_runner_(
+            new test::FakeSingleThreadTaskRunner(testing_clock_)),
         cast_environment_(new CastEnvironment(
             scoped_ptr<base::TickClock>(testing_clock_).Pass(),
             task_runner_,
@@ -494,8 +495,8 @@ class End2EndTest : public ::testing::Test {
 
   base::TimeTicks start_time_;
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
-  scoped_refptr<test::FakeTaskRunner> transport_task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> transport_task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
 
   LoopBackTransport receiver_to_sender_;
diff --git a/media/cast/test/fake_gpu_video_accelerator_factories.cc b/media/cast/test/fake_gpu_video_accelerator_factories.cc
index e405cf2..b9f16a5 100644
--- a/media/cast/test/fake_gpu_video_accelerator_factories.cc
+++ b/media/cast/test/fake_gpu_video_accelerator_factories.cc
@@ -12,7 +12,7 @@ namespace cast {
 namespace test {
 
 FakeGpuVideoAcceleratorFactories::FakeGpuVideoAcceleratorFactories(
-    const scoped_refptr<base::TaskRunner>& fake_task_runner)
+    const scoped_refptr<base::SingleThreadTaskRunner>& fake_task_runner)
     : fake_task_runner_(fake_task_runner) {}
 
 FakeGpuVideoAcceleratorFactories::~FakeGpuVideoAcceleratorFactories() {}
@@ -35,8 +35,7 @@ base::SharedMemory* FakeGpuVideoAcceleratorFactories::CreateSharedMemory(
 
 scoped_refptr<base::SingleThreadTaskRunner>
 FakeGpuVideoAcceleratorFactories::GetTaskRunner() {
-  return scoped_refptr<base::SingleThreadTaskRunner>(
-      static_cast<base::SingleThreadTaskRunner*>(fake_task_runner_.get()));
+  return fake_task_runner_;
 }
 
 uint32 FakeGpuVideoAcceleratorFactories::CreateTextures(
diff --git a/media/cast/test/fake_gpu_video_accelerator_factories.h b/media/cast/test/fake_gpu_video_accelerator_factories.h
index 435a18e..4cc2182 100644
--- a/media/cast/test/fake_gpu_video_accelerator_factories.h
+++ b/media/cast/test/fake_gpu_video_accelerator_factories.h
@@ -8,7 +8,7 @@
 #include "media/filters/gpu_video_accelerator_factories.h"
 
 #include "base/message_loop/message_loop.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 
 namespace media {
 namespace cast {
@@ -17,14 +17,15 @@ namespace test {
 class FakeGpuVideoAcceleratorFactories : public GpuVideoAcceleratorFactories {
  public:
   explicit FakeGpuVideoAcceleratorFactories(
-      const scoped_refptr<base::TaskRunner>& fake_task_runner);
+      const scoped_refptr<base::SingleThreadTaskRunner>& fake_task_runner);
 
   virtual scoped_ptr<VideoEncodeAccelerator> CreateVideoEncodeAccelerator(
       VideoEncodeAccelerator::Client* client) OVERRIDE;
 
   virtual base::SharedMemory* CreateSharedMemory(size_t size) OVERRIDE;
 
-  virtual scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() OVERRIDE;
+  virtual scoped_refptr<base::SingleThreadTaskRunner>
+      GetTaskRunner() OVERRIDE;
   //
   //  The following functions are no-op.
   //
@@ -54,7 +55,7 @@ class FakeGpuVideoAcceleratorFactories : public GpuVideoAcceleratorFactories {
   friend class base::RefCountedThreadSafe<FakeGpuVideoAcceleratorFactories>;
   virtual ~FakeGpuVideoAcceleratorFactories();
 
-  const scoped_refptr<base::TaskRunner> fake_task_runner_;
+  const scoped_refptr<base::SingleThreadTaskRunner> fake_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeGpuVideoAcceleratorFactories);
 };
diff --git a/media/cast/test/fake_task_runner.cc b/media/cast/test/fake_single_thread_task_runner.cc
index 29a74f8..d2950fd 100644
--- a/media/cast/test/fake_task_runner.cc
+++ b/media/cast/test/fake_single_thread_task_runner.cc
@@ -1,9 +1,10 @@
-// Copyright 2013 The Chromium Authors. All rights reserved.
+// 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 "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 
+#include "base/logging.h"
 #include "base/time/tick_clock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -11,14 +12,16 @@ namespace media {
 namespace cast {
 namespace test {
 
-FakeTaskRunner::FakeTaskRunner(base::SimpleTestTickClock* clock)
+FakeSingleThreadTaskRunner::FakeSingleThreadTaskRunner(
+    base::SimpleTestTickClock* clock)
     : clock_(clock) {}
 
-FakeTaskRunner::~FakeTaskRunner() {}
+FakeSingleThreadTaskRunner::~FakeSingleThreadTaskRunner() {}
 
-bool FakeTaskRunner::PostDelayedTask(const tracked_objects::Location& from_here,
-                                     const base::Closure& task,
-                                     base::TimeDelta delay) {
+bool FakeSingleThreadTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task,
+    base::TimeDelta delay) {
   EXPECT_GE(delay, base::TimeDelta());
   PostedTask posed_task(from_here,
                         task,
@@ -30,10 +33,12 @@ bool FakeTaskRunner::PostDelayedTask(const tracked_objects::Location& from_here,
   return false;
 }
 
-bool FakeTaskRunner::RunsTasksOnCurrentThread() const { return true; }
+bool FakeSingleThreadTaskRunner::RunsTasksOnCurrentThread() const {
+  return true;
+}
 
-void FakeTaskRunner::RunTasks() {
-  for (;;) {
+void FakeSingleThreadTaskRunner::RunTasks() {
+  while(true) {
     // Run all tasks equal or older than current time.
     std::multimap<base::TimeTicks, PostedTask>::iterator it = tasks_.begin();
     if (it == tasks_.end())
@@ -48,6 +53,14 @@ void FakeTaskRunner::RunTasks() {
   }
 }
 
+bool FakeSingleThreadTaskRunner::PostNonNestableDelayedTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task,
+    base::TimeDelta delay) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
 }  // namespace test
 }  // namespace cast
 }  // namespace media
diff --git a/media/cast/test/fake_task_runner.h b/media/cast/test/fake_single_thread_task_runner.h
index 33a549f..7101385 100644
--- a/media/cast/test/fake_task_runner.h
+++ b/media/cast/test/fake_single_thread_task_runner.h
@@ -1,4 +1,4 @@
-// Copyright 2013 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -8,7 +8,7 @@
 #include <map>
 
 #include "base/basictypes.h"
-#include "base/task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "base/test/test_pending_task.h"
 
@@ -18,27 +18,33 @@ namespace test {
 
 typedef base::TestPendingTask PostedTask;
 
-class FakeTaskRunner : public base::TaskRunner {
+class FakeSingleThreadTaskRunner : public base::SingleThreadTaskRunner {
  public:
-  explicit FakeTaskRunner(base::SimpleTestTickClock* clock);
+  explicit FakeSingleThreadTaskRunner(base::SimpleTestTickClock* clock);
 
   void RunTasks();
 
-  // base::TaskRunner implementation.
+  // base::SingleThreadTaskRunner implementation.
   virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
                                const base::Closure& task,
                                base::TimeDelta delay) OVERRIDE;
 
   virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
 
+  // This function is currently not used, and will return false.
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      const base::Closure& task,
+      base::TimeDelta delay) OVERRIDE;
+
  protected:
-  virtual ~FakeTaskRunner();
+  virtual ~FakeSingleThreadTaskRunner();
 
  private:
   base::SimpleTestTickClock* const clock_;
   std::multimap<base::TimeTicks, PostedTask> tasks_;
 
-  DISALLOW_COPY_AND_ASSIGN(FakeTaskRunner);
+  DISALLOW_COPY_AND_ASSIGN(FakeSingleThreadTaskRunner);
 };
 
 }  // namespace test
diff --git a/media/cast/test/sender.cc b/media/cast/test/sender.cc
index 2d53647..32c0e37 100644
--- a/media/cast/test/sender.cc
+++ b/media/cast/test/sender.cc
@@ -186,7 +186,7 @@ VideoSenderConfig GetVideoSenderConfig() {
 
 class SendProcess {
  public:
-  SendProcess(scoped_refptr<base::TaskRunner> thread_proxy,
+  SendProcess(scoped_refptr<base::SingleThreadTaskRunner> thread_proxy,
               base::TickClock* clock,
               const VideoSenderConfig& video_config,
               FrameInput* frame_input)
@@ -281,7 +281,7 @@ class SendProcess {
   }
 
  private:
-  scoped_refptr<base::TaskRunner> test_app_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> test_app_thread_proxy_;
   const VideoSenderConfig video_config_;
   int audio_diff_;
   const scoped_refptr<FrameInput> frame_input_;
diff --git a/media/cast/test/utility/utility.gyp b/media/cast/test/utility/utility.gyp
index 01a3c4a..93e2f14 100644
--- a/media/cast/test/utility/utility.gyp
+++ b/media/cast/test/utility/utility.gyp
@@ -18,8 +18,8 @@
 
       ],
       'sources': [
-        '<(DEPTH)/media/cast/test/fake_task_runner.cc',
-        '<(DEPTH)/media/cast/test/fake_task_runner.h',
+        '<(DEPTH)/media/cast/test/fake_single_thread_task_runner.cc',
+        '<(DEPTH)/media/cast/test/fake_single_thread_task_runner.h',
         'input_builder.cc',
         'input_builder.h',
         'audio_utility.cc',
diff --git a/media/cast/transport/cast_transport_sender.h b/media/cast/transport/cast_transport_sender.h
index 051a5b8..553f3e3 100644
--- a/media/cast/transport/cast_transport_sender.h
+++ b/media/cast/transport/cast_transport_sender.h
@@ -25,7 +25,7 @@
 
 #include "base/basictypes.h"
 #include "base/callback.h"
-#include "base/task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time/tick_clock.h"
 #include "media/cast/transport/cast_transport_config.h"
@@ -45,7 +45,7 @@ class CastTransportSender : public base::NonThreadSafe {
       base::TickClock* clock,
       const CastTransportConfig& config,
       const CastTransportStatusCallback& status_callback,
-      const scoped_refptr<base::TaskRunner>& transport_task_runner);
+      const scoped_refptr<base::SingleThreadTaskRunner>& transport_task_runner);
 
   virtual ~CastTransportSender() {}
 
diff --git a/media/cast/transport/cast_transport_sender_impl.cc b/media/cast/transport/cast_transport_sender_impl.cc
index 3c23ad0..9b5592a 100644
--- a/media/cast/transport/cast_transport_sender_impl.cc
+++ b/media/cast/transport/cast_transport_sender_impl.cc
@@ -4,7 +4,7 @@
 
 #include "media/cast/transport/cast_transport_sender_impl.h"
 
-#include "base/task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "media/cast/transport/cast_transport_config.h"
 #include "media/cast/transport/cast_transport_defines.h"
 
@@ -16,7 +16,7 @@ CastTransportSender* CastTransportSender::CreateCastTransportSender(
     base::TickClock* clock,
     const CastTransportConfig& config,
     const CastTransportStatusCallback& status_callback,
-    const scoped_refptr<base::TaskRunner>& transport_task_runner) {
+    const scoped_refptr<base::SingleThreadTaskRunner>& transport_task_runner) {
   return new CastTransportSenderImpl(clock,
                                      config,
                                      status_callback,
@@ -28,7 +28,7 @@ CastTransportSenderImpl::CastTransportSenderImpl(
     base::TickClock* clock,
     const CastTransportConfig& config,
     const CastTransportStatusCallback& status_callback,
-    const scoped_refptr<base::TaskRunner>& transport_task_runner,
+    const scoped_refptr<base::SingleThreadTaskRunner>& transport_task_runner,
     PacketSender* external_transport)
     : transport_(external_transport ? NULL :
                  new UdpTransport(transport_task_runner,
diff --git a/media/cast/transport/cast_transport_sender_impl.h b/media/cast/transport/cast_transport_sender_impl.h
index 343a65e..b4589ca 100644
--- a/media/cast/transport/cast_transport_sender_impl.h
+++ b/media/cast/transport/cast_transport_sender_impl.h
@@ -30,7 +30,7 @@ class CastTransportSenderImpl : public CastTransportSender {
       base::TickClock* clock,
       const CastTransportConfig& config,
       const CastTransportStatusCallback& status_callback,
-      const scoped_refptr<base::TaskRunner>& transport_task_runner,
+      const scoped_refptr<base::SingleThreadTaskRunner>& transport_task_runner,
       PacketSender* external_transport);
 
   virtual ~CastTransportSenderImpl();
diff --git a/media/cast/transport/pacing/paced_sender.cc b/media/cast/transport/pacing/paced_sender.cc
index b592b0a..46b0776 100644
--- a/media/cast/transport/pacing/paced_sender.cc
+++ b/media/cast/transport/pacing/paced_sender.cc
@@ -22,7 +22,7 @@ static const size_t kPacingMaxBurstsPerFrame = 3;
 PacedSender::PacedSender(
     base::TickClock* clock,
     PacketSender* transport,
-    const scoped_refptr<base::TaskRunner>& transport_task_runner)
+    const scoped_refptr<base::SingleThreadTaskRunner>& transport_task_runner)
     : clock_(clock),
       transport_(transport),
       transport_task_runner_(transport_task_runner),
@@ -47,8 +47,8 @@ bool PacedSender::SendPacketsToTransport(const PacketList& packets,
   UpdateBurstSize(packets.size());
 
   if (!packets_not_sent->empty()) {
-    packets_not_sent->insert(packets_not_sent->end(),
-                             packets.begin(), packets.end());
+    packets_not_sent->insert(
+        packets_not_sent->end(), packets.begin(), packets.end());
     return true;
   }
 
@@ -58,17 +58,18 @@ bool PacedSender::SendPacketsToTransport(const PacketList& packets,
   size_t max_packets_to_send_now = burst_size_ - packets_sent_in_burst_;
 
   if (max_packets_to_send_now > 0) {
-    size_t packets_to_send_now = std::min(max_packets_to_send_now,
-                                          packets.size());
+    size_t packets_to_send_now =
+        std::min(max_packets_to_send_now, packets.size());
 
     std::advance(first_to_store_it, packets_to_send_now);
-    packets_to_send.insert(packets_to_send.begin(),
-                           packets.begin(), first_to_store_it);
+    packets_to_send.insert(
+        packets_to_send.begin(), packets.begin(), first_to_store_it);
   }
-  packets_not_sent->insert(packets_not_sent->end(),
-                         first_to_store_it, packets.end());
+  packets_not_sent->insert(
+      packets_not_sent->end(), first_to_store_it, packets.end());
   packets_sent_in_burst_ += packets_to_send.size();
-  if (packets_to_send.empty()) return true;
+  if (packets_to_send.empty())
+    return true;
 
   return TransmitPackets(packets_to_send);
 }
@@ -79,12 +80,14 @@ bool PacedSender::SendRtcpPacket(const Packet& packet) {
 }
 
 void PacedSender::ScheduleNextSend() {
-  base::TimeDelta time_to_next = time_last_process_ -
-      clock_->NowTicks() + base::TimeDelta::FromMilliseconds(kPacingIntervalMs);
+  base::TimeDelta time_to_next =
+      time_last_process_ - clock_->NowTicks() +
+      base::TimeDelta::FromMilliseconds(kPacingIntervalMs);
 
   time_to_next = std::max(time_to_next, base::TimeDelta());
 
-  transport_task_runner_->PostDelayedTask(FROM_HERE,
+  transport_task_runner_->PostDelayedTask(
+      FROM_HERE,
       base::Bind(&PacedSender::SendNextPacketBurst, weak_factory_.GetWeakPtr()),
       time_to_next);
 }
@@ -96,7 +99,8 @@ void PacedSender::SendNextPacketBurst() {
 }
 
 void PacedSender::SendStoredPackets() {
-  if (packet_list_.empty() && resend_packet_list_.empty()) return;
+  if (packet_list_.empty() && resend_packet_list_.empty())
+    return;
 
   size_t packets_to_send = burst_size_;
   PacketList packets_to_resend;
@@ -104,22 +108,20 @@ void PacedSender::SendStoredPackets() {
   // Send our re-send packets first.
   if (!resend_packet_list_.empty()) {
     PacketList::iterator it = resend_packet_list_.begin();
-    size_t packets_to_send_now = std::min(packets_to_send,
-                                          resend_packet_list_.size());
+    size_t packets_to_send_now =
+        std::min(packets_to_send, resend_packet_list_.size());
     std::advance(it, packets_to_send_now);
-    packets_to_resend.insert(packets_to_resend.begin(),
-                             resend_packet_list_.begin(), it);
+    packets_to_resend.insert(
+        packets_to_resend.begin(), resend_packet_list_.begin(), it);
     resend_packet_list_.erase(resend_packet_list_.begin(), it);
     packets_to_send -= packets_to_resend.size();
   }
   if (!packet_list_.empty() && packets_to_send > 0) {
     PacketList::iterator it = packet_list_.begin();
-    size_t packets_to_send_now = std::min(packets_to_send,
-                                          packet_list_.size());
+    size_t packets_to_send_now = std::min(packets_to_send, packet_list_.size());
 
     std::advance(it, packets_to_send_now);
-    packets_to_resend.insert(packets_to_resend.end(),
-                             packet_list_.begin(), it);
+    packets_to_resend.insert(packets_to_resend.end(), packet_list_.begin(), it);
     packet_list_.erase(packet_list_.begin(), it);
 
     if (packet_list_.empty()) {
@@ -140,11 +142,11 @@ bool PacedSender::TransmitPackets(const PacketList& packets) {
 
 void PacedSender::UpdateBurstSize(size_t packets_to_send) {
   packets_to_send = std::max(packets_to_send,
-      resend_packet_list_.size() + packet_list_.size());
+                             resend_packet_list_.size() + packet_list_.size());
 
   packets_to_send += (kPacingMaxBurstsPerFrame - 1);  // Round up.
-  burst_size_ = std::max(packets_to_send / kPacingMaxBurstsPerFrame,
-                         burst_size_);
+  burst_size_ =
+      std::max(packets_to_send / kPacingMaxBurstsPerFrame, burst_size_);
 }
 
 }  // namespace transport
diff --git a/media/cast/transport/pacing/paced_sender.h b/media/cast/transport/pacing/paced_sender.h
index 2f3428a..80e2b3f 100644
--- a/media/cast/transport/pacing/paced_sender.h
+++ b/media/cast/transport/pacing/paced_sender.h
@@ -11,7 +11,7 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
-#include "base/task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time/default_tick_clock.h"
 #include "base/time/tick_clock.h"
@@ -40,9 +40,12 @@ class PacedSender : public PacedPacketSender,
                     public base::NonThreadSafe,
                     public base::SupportsWeakPtr<PacedSender> {
  public:
-  PacedSender(base::TickClock* clock,
-              PacketSender* transport,
-              const scoped_refptr<base::TaskRunner>& transport_task_runner);
+  // The |external_transport| should only be used by the Cast receiver and for
+  // testing.
+  PacedSender(
+      base::TickClock* clock,
+      PacketSender* external_transport,
+      const scoped_refptr<base::SingleThreadTaskRunner>& transport_task_runner);
 
   virtual ~PacedSender();
 
@@ -74,7 +77,6 @@ class PacedSender : public PacedPacketSender,
   base::TickClock* const clock_;
   PacketSender* transport_;  // Not owned by this class.
   scoped_refptr<base::TaskRunner> transport_task_runner_;
-
   size_t burst_size_;
   size_t packets_sent_in_burst_;
   base::TimeTicks time_last_process_;
diff --git a/media/cast/transport/pacing/paced_sender_unittest.cc b/media/cast/transport/pacing/paced_sender_unittest.cc
index 05d1683..04bd437 100644
--- a/media/cast/transport/pacing/paced_sender_unittest.cc
+++ b/media/cast/transport/pacing/paced_sender_unittest.cc
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/test/simple_test_tick_clock.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/pacing/paced_sender.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -46,7 +46,7 @@ class PacedSenderTest : public ::testing::Test {
   PacedSenderTest() {
     testing_clock_.Advance(
         base::TimeDelta::FromMilliseconds(kStartMillisecond));
-    task_runner_ = new test::FakeTaskRunner(&testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(&testing_clock_);
     paced_sender_.reset(new PacedSender(&testing_clock_,
                                         &mock_transport_,
                                         task_runner_));
@@ -68,7 +68,7 @@ class PacedSenderTest : public ::testing::Test {
 
   base::SimpleTestTickClock testing_clock_;
   TestPacketSender mock_transport_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<PacedSender> paced_sender_;
 };
 
diff --git a/media/cast/transport/rtcp/rtcp_builder_unittest.cc b/media/cast/transport/rtcp/rtcp_builder_unittest.cc
index 439df48..1de8755 100644
--- a/media/cast/transport/rtcp/rtcp_builder_unittest.cc
+++ b/media/cast/transport/rtcp/rtcp_builder_unittest.cc
@@ -8,7 +8,7 @@
 #include "media/cast/cast_environment.h"
 #include "media/cast/rtcp/rtcp_utility.h"
 #include "media/cast/rtcp/test_rtcp_packet_builder.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/pacing/paced_sender.h"
 #include "media/cast/transport/rtcp/rtcp_builder.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -59,7 +59,7 @@ class TestRtcpTransport : public PacedPacketSender {
 class RtcpBuilderTest : public ::testing::Test {
  protected:
   RtcpBuilderTest()
-      : task_runner_(new test::FakeTaskRunner(&testing_clock_)),
+      : task_runner_(new test::FakeSingleThreadTaskRunner(&testing_clock_)),
         cast_environment_(new CastEnvironment(&testing_clock_, task_runner_,
             task_runner_, task_runner_, task_runner_, task_runner_,
             GetDefaultCastSenderLoggingConfig())),
@@ -68,7 +68,7 @@ class RtcpBuilderTest : public ::testing::Test {
 
   base::SimpleTestTickClock testing_clock_;
   TestRtcpTransport test_transport_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   scoped_ptr<RtcpBuilder> rtcp_builder_;
 };
diff --git a/media/cast/transport/rtp_sender/rtp_packetizer/rtp_packetizer_unittest.cc b/media/cast/transport/rtp_sender/rtp_packetizer/rtp_packetizer_unittest.cc
index bc83f9c..0fb50a4 100644
--- a/media/cast/transport/rtp_sender/rtp_packetizer/rtp_packetizer_unittest.cc
+++ b/media/cast/transport/rtp_sender/rtp_packetizer/rtp_packetizer_unittest.cc
@@ -6,7 +6,7 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "base/test/simple_test_tick_clock.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/pacing/paced_sender.h"
 #include "media/cast/transport/rtp_sender/packet_storage/packet_storage.h"
 #include "media/cast/transport/rtp_sender/rtp_packetizer/test/rtp_header_parser.h"
@@ -93,7 +93,7 @@ class TestRtpPacketTransport : public PacketSender {
 class RtpPacketizerTest : public ::testing::Test {
  protected:
   RtpPacketizerTest()
-      : task_runner_(new test::FakeTaskRunner(&testing_clock_)),
+      : task_runner_(new test::FakeSingleThreadTaskRunner(&testing_clock_)),
         video_frame_(),
         packet_storage_(&testing_clock_, kMaxPacketStorageTimeMs) {
     config_.sequence_number = kSeqNum;
@@ -123,7 +123,7 @@ class RtpPacketizerTest : public ::testing::Test {
   }
 
   base::SimpleTestTickClock testing_clock_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   EncodedVideoFrame video_frame_;
   PacketStorage packet_storage_;
   RtpPacketizerConfig config_;
diff --git a/media/cast/transport/transport/udp_transport.cc b/media/cast/transport/transport/udp_transport.cc
index f1795e8..65962e2 100644
--- a/media/cast/transport/transport/udp_transport.cc
+++ b/media/cast/transport/transport/udp_transport.cc
@@ -41,7 +41,7 @@ bool IsEqual(const net::IPEndPoint& addr1, const net::IPEndPoint& addr2) {
 }  // namespace
 
 UdpTransport::UdpTransport(
-    const scoped_refptr<base::TaskRunner>& io_thread_proxy,
+    const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_proxy,
     const net::IPEndPoint& local_end_point,
     const net::IPEndPoint& remote_end_point,
     const CastTransportStatusCallback& status_callback)
diff --git a/media/cast/transport/transport/udp_transport.h b/media/cast/transport/transport/udp_transport.h
index 2f35417..1087c57 100644
--- a/media/cast/transport/transport/udp_transport.h
+++ b/media/cast/transport/transport/udp_transport.h
@@ -33,10 +33,11 @@ class UdpTransport : public PacketSender {
   // |remote_end_point| specifies the address and port to send packets
   // to. If the value is 0.0.0.0:0 the the end point is set to the source
   // address of the first packet received.
-  UdpTransport(const scoped_refptr<base::TaskRunner>& io_thread_proxy,
-               const net::IPEndPoint& local_end_point,
-               const net::IPEndPoint& remote_end_point,
-               const CastTransportStatusCallback& status_callback);
+  UdpTransport(
+      const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_proxy,
+      const net::IPEndPoint& local_end_point,
+      const net::IPEndPoint& remote_end_point,
+      const CastTransportStatusCallback& status_callback);
   virtual ~UdpTransport();
 
   // Start receiving packets. Packets are submitted to |packet_receiver|.
@@ -50,7 +51,7 @@ class UdpTransport : public PacketSender {
   void OnReceived(int result);
   void OnSent(const scoped_refptr<net::IOBuffer>& buf, int result);
 
-  scoped_refptr<base::TaskRunner> io_thread_proxy_;
+  scoped_refptr<base::SingleThreadTaskRunner> io_thread_proxy_;
   net::IPEndPoint local_addr_;
   net::IPEndPoint remote_addr_;
   scoped_ptr<net::UDPServerSocket> udp_socket_;
diff --git a/media/cast/video_receiver/video_decoder_unittest.cc b/media/cast/video_receiver/video_decoder_unittest.cc
index 76e7e27..9b6f9b9 100644
--- a/media/cast/video_receiver/video_decoder_unittest.cc
+++ b/media/cast/video_receiver/video_decoder_unittest.cc
@@ -10,7 +10,7 @@
 #include "media/cast/cast_defines.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/cast_receiver.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/video_receiver/video_decoder.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -41,7 +41,7 @@ class VideoDecoderTest : public ::testing::Test {
  protected:
   VideoDecoderTest()
       : testing_clock_(new base::SimpleTestTickClock()),
-        task_runner_(new test::FakeTaskRunner(testing_clock_)),
+        task_runner_(new test::FakeSingleThreadTaskRunner(testing_clock_)),
         cast_environment_(new CastEnvironment(
             scoped_ptr<base::TickClock>(testing_clock_), task_runner_,
             task_runner_, task_runner_, task_runner_, task_runner_,
@@ -60,7 +60,7 @@ class VideoDecoderTest : public ::testing::Test {
   scoped_ptr<VideoDecoder> decoder_;
   VideoReceiverConfig config_;
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   scoped_refptr<DecodeTestFrameCallback> test_callback_;
 };
diff --git a/media/cast/video_receiver/video_receiver_unittest.cc b/media/cast/video_receiver/video_receiver_unittest.cc
index 765c85f..3580511 100644
--- a/media/cast/video_receiver/video_receiver_unittest.cc
+++ b/media/cast/video_receiver/video_receiver_unittest.cc
@@ -8,7 +8,7 @@
 #include "base/test/simple_test_tick_clock.h"
 #include "media/cast/cast_defines.h"
 #include "media/cast/cast_environment.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/transport/pacing/mock_paced_packet_sender.h"
 #include "media/cast/video_receiver/video_receiver.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -72,7 +72,7 @@ class VideoReceiverTest : public ::testing::Test {
     config_.codec = transport::kVp8;
     config_.use_external_decoder = false;
     testing_clock_ = new base::SimpleTestTickClock();
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ = new CastEnvironment(
         scoped_ptr<base::TickClock>(testing_clock_).Pass(), task_runner_,
         task_runner_, task_runner_, task_runner_, task_runner_,
@@ -105,7 +105,7 @@ class VideoReceiverTest : public ::testing::Test {
   RtpCastHeader rtp_header_;
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
 
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_refptr<CastEnvironment> cast_environment_;
   scoped_refptr<TestVideoReceiverCallback> video_receiver_callback_;
 };
diff --git a/media/cast/video_sender/external_video_encoder_unittest.cc b/media/cast/video_sender/external_video_encoder_unittest.cc
index f932cb53..4e97416 100644
--- a/media/cast/video_sender/external_video_encoder_unittest.cc
+++ b/media/cast/video_sender/external_video_encoder_unittest.cc
@@ -11,7 +11,7 @@
 #include "media/cast/cast_defines.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/test/fake_gpu_video_accelerator_factories.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/test/fake_video_encode_accelerator.h"
 #include "media/cast/test/utility/video_utility.h"
 #include "media/cast/video_sender/external_video_encoder.h"
@@ -90,7 +90,7 @@ class ExternalVideoEncoderTest : public ::testing::Test {
 
   virtual void SetUp() {
     testing_clock_ = new base::SimpleTestTickClock();
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ = new CastEnvironment(
         scoped_ptr<base::TickClock>(testing_clock_).Pass(), task_runner_,
         task_runner_, task_runner_, task_runner_, task_runner_, task_runner_,
@@ -104,7 +104,7 @@ class ExternalVideoEncoderTest : public ::testing::Test {
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
   scoped_refptr<TestVideoEncoderCallback> test_video_encoder_callback_;
   VideoSenderConfig video_config_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<VideoEncoder> video_encoder_;
   scoped_refptr<media::VideoFrame> video_frame_;
   scoped_refptr<CastEnvironment> cast_environment_;
diff --git a/media/cast/video_sender/video_encoder_impl_unittest.cc b/media/cast/video_sender/video_encoder_impl_unittest.cc
index 0ae009b..22855cf8 100644
--- a/media/cast/video_sender/video_encoder_impl_unittest.cc
+++ b/media/cast/video_sender/video_encoder_impl_unittest.cc
@@ -10,7 +10,7 @@
 #include "media/base/video_frame.h"
 #include "media/cast/cast_defines.h"
 #include "media/cast/cast_environment.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/test/utility/video_utility.h"
 #include "media/cast/video_sender/video_encoder_impl.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -87,7 +87,7 @@ class VideoEncoderImplTest : public ::testing::Test {
 
   virtual void SetUp() OVERRIDE {
     testing_clock_ = new base::SimpleTestTickClock();
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ = new CastEnvironment(
         scoped_ptr<base::TickClock>(testing_clock_).Pass(), task_runner_,
         task_runner_, task_runner_, task_runner_, task_runner_,
@@ -107,7 +107,7 @@ class VideoEncoderImplTest : public ::testing::Test {
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
   scoped_refptr<TestVideoEncoderCallback> test_video_encoder_callback_;
   VideoSenderConfig video_config_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<VideoEncoder> video_encoder_;
   scoped_refptr<media::VideoFrame> video_frame_;
 
diff --git a/media/cast/video_sender/video_sender_unittest.cc b/media/cast/video_sender/video_sender_unittest.cc
index add51a3..a5871ce 100644
--- a/media/cast/video_sender/video_sender_unittest.cc
+++ b/media/cast/video_sender/video_sender_unittest.cc
@@ -10,7 +10,7 @@
 #include "media/base/video_frame.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/test/fake_gpu_video_accelerator_factories.h"
-#include "media/cast/test/fake_task_runner.h"
+#include "media/cast/test/fake_single_thread_task_runner.h"
 #include "media/cast/test/utility/video_utility.h"
 #include "media/cast/transport/cast_transport_config.h"
 #include "media/cast/transport/cast_transport_sender_impl.h"
@@ -85,7 +85,7 @@ class VideoSenderTest : public ::testing::Test {
     testing_clock_ = new base::SimpleTestTickClock();
     testing_clock_->Advance(
         base::TimeDelta::FromMilliseconds(kStartMillisecond));
-    task_runner_ = new test::FakeTaskRunner(testing_clock_);
+    task_runner_ = new test::FakeSingleThreadTaskRunner(testing_clock_);
     cast_environment_ = new CastEnvironment(
         scoped_ptr<base::TickClock>(testing_clock_).Pass(),
         task_runner_, task_runner_, task_runner_, task_runner_,
@@ -170,7 +170,7 @@ class VideoSenderTest : public ::testing::Test {
   base::SimpleTestTickClock* testing_clock_;  // Owned by CastEnvironment.
   TestPacketSender transport_;
   scoped_ptr<transport::CastTransportSenderImpl> transport_sender_;
-  scoped_refptr<test::FakeTaskRunner> task_runner_;
+  scoped_refptr<test::FakeSingleThreadTaskRunner> task_runner_;
   scoped_ptr<PeerVideoSender> video_sender_;
   scoped_refptr<CastEnvironment> cast_environment_;