diff --git a/talk/app/webrtc/mediastream_unittest.cc b/talk/app/webrtc/mediastream_unittest.cc
new file mode 100644
index 0000000..bb2d50e
--- /dev/null
+++ b/talk/app/webrtc/mediastream_unittest.cc
@@ -0,0 +1,162 @@
+/*
+ * libjingle
+ * Copyright 2011, Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *  3. The name of the author may not be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <string>
+
+#include "talk/app/webrtc/audiotrack.h"
+#include "talk/app/webrtc/mediastream.h"
+#include "talk/app/webrtc/videotrack.h"
+#include "talk/base/refcount.h"
+#include "talk/base/scoped_ptr.h"
+#include "talk/base/gunit.h"
+#include "testing/base/public/gmock.h"
+
+static const char kStreamLabel1[] = "local_stream_1";
+static const char kVideoTrackId[] = "dummy_video_cam_1";
+static const char kAudioTrackId[] = "dummy_microphone_1";
+
+using talk_base::scoped_refptr;
+using ::testing::Exactly;
+
+namespace webrtc {
+
+// Helper class to test Observer.
+class MockObserver : public ObserverInterface {
+ public:
+  MockObserver() {}
+
+  MOCK_METHOD0(OnChanged, void());
+};
+
+class MediaStreamTest: public testing::Test {
+ protected:
+  virtual void SetUp() {
+    stream_ = MediaStream::Create(kStreamLabel1);
+    ASSERT_TRUE(stream_.get() != NULL);
+
+    video_track_ = VideoTrack::Create(kVideoTrackId, NULL);
+    ASSERT_TRUE(video_track_.get() != NULL);
+    EXPECT_EQ(MediaStreamTrackInterface::kInitializing, video_track_->state());
+
+    audio_track_ = AudioTrack::Create(kAudioTrackId, NULL);
+
+    ASSERT_TRUE(audio_track_.get() != NULL);
+    EXPECT_EQ(MediaStreamTrackInterface::kInitializing, audio_track_->state());
+
+    EXPECT_TRUE(stream_->AddTrack(video_track_));
+    EXPECT_FALSE(stream_->AddTrack(video_track_));
+    EXPECT_TRUE(stream_->AddTrack(audio_track_));
+    EXPECT_FALSE(stream_->AddTrack(audio_track_));
+  }
+
+  void ChangeTrack(MediaStreamTrackInterface* track) {
+    MockObserver observer;
+    track->RegisterObserver(&observer);
+
+    EXPECT_CALL(observer, OnChanged())
+        .Times(Exactly(1));
+    track->set_enabled(false);
+    EXPECT_FALSE(track->enabled());
+
+    EXPECT_CALL(observer, OnChanged())
+        .Times(Exactly(1));
+    track->set_state(MediaStreamTrackInterface::kLive);
+    EXPECT_EQ(MediaStreamTrackInterface::kLive, track->state());
+  }
+
+  scoped_refptr<MediaStreamInterface> stream_;
+  scoped_refptr<AudioTrackInterface> audio_track_;
+  scoped_refptr<VideoTrackInterface> video_track_;
+};
+
+TEST_F(MediaStreamTest, GetTrackInfo) {
+  ASSERT_EQ(1u, stream_->GetVideoTracks().size());
+  ASSERT_EQ(1u, stream_->GetAudioTracks().size());
+
+  // Verify the video track.
+  scoped_refptr<webrtc::MediaStreamTrackInterface> video_track(
+      stream_->GetVideoTracks()[0]);
+  EXPECT_EQ(0, video_track->id().compare(kVideoTrackId));
+  EXPECT_TRUE(video_track->enabled());
+
+  ASSERT_EQ(1u, stream_->GetVideoTracks().size());
+  EXPECT_TRUE(stream_->GetVideoTracks()[0].get() == video_track.get());
+  EXPECT_TRUE(stream_->FindVideoTrack(video_track->id()).get()
+              == video_track.get());
+  video_track = stream_->GetVideoTracks()[0];
+  EXPECT_EQ(0, video_track->id().compare(kVideoTrackId));
+  EXPECT_TRUE(video_track->enabled());
+
+  // Verify the audio track.
+  scoped_refptr<webrtc::MediaStreamTrackInterface> audio_track(
+      stream_->GetAudioTracks()[0]);
+  EXPECT_EQ(0, audio_track->id().compare(kAudioTrackId));
+  EXPECT_TRUE(audio_track->enabled());
+  ASSERT_EQ(1u, stream_->GetAudioTracks().size());
+  EXPECT_TRUE(stream_->GetAudioTracks()[0].get() == audio_track.get());
+  EXPECT_TRUE(stream_->FindAudioTrack(audio_track->id()).get()
+              == audio_track.get());
+  audio_track = stream_->GetAudioTracks()[0];
+  EXPECT_EQ(0, audio_track->id().compare(kAudioTrackId));
+  EXPECT_TRUE(audio_track->enabled());
+}
+
+TEST_F(MediaStreamTest, RemoveTrack) {
+  MockObserver observer;
+  stream_->RegisterObserver(&observer);
+
+  EXPECT_CALL(observer, OnChanged())
+      .Times(Exactly(2));
+
+  EXPECT_TRUE(stream_->RemoveTrack(audio_track_));
+  EXPECT_FALSE(stream_->RemoveTrack(audio_track_));
+  EXPECT_EQ(0u, stream_->GetAudioTracks().size());
+  EXPECT_EQ(0u, stream_->GetAudioTracks().size());
+
+  EXPECT_TRUE(stream_->RemoveTrack(video_track_));
+  EXPECT_FALSE(stream_->RemoveTrack(video_track_));
+
+  EXPECT_EQ(0u, stream_->GetVideoTracks().size());
+  EXPECT_EQ(0u, stream_->GetVideoTracks().size());
+
+  EXPECT_FALSE(stream_->RemoveTrack(static_cast<AudioTrackInterface*>(NULL)));
+  EXPECT_FALSE(stream_->RemoveTrack(static_cast<VideoTrackInterface*>(NULL)));
+}
+
+TEST_F(MediaStreamTest, ChangeVideoTrack) {
+  scoped_refptr<webrtc::VideoTrackInterface> video_track(
+      stream_->GetVideoTracks()[0]);
+  ChangeTrack(video_track.get());
+}
+
+TEST_F(MediaStreamTest, ChangeAudioTrack) {
+  scoped_refptr<webrtc::AudioTrackInterface> audio_track(
+      stream_->GetAudioTracks()[0]);
+  ChangeTrack(audio_track.get());
+}
+
+}  // namespace webrtc