Convert video capture pipline to base::TimeTicks

base::TimeTicks is a monotonic clock, unlike base::Time, which may change if
the system time is changed.  Switch over the video capture pipeline to use this
clock.

BUG=249215
TEST=local build, run on CrOS snow, desktop Linux

Review URL: https://codereview.chromium.org/101843005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243493 0039d316-1c4b-4281-b951-d872f2087c98

31 files changed, 168 insertions, 152 deletions

diff --git a/content/browser/gpu/gpu_process_host.cc b/content/browser/gpu/gpu_process_host.cc
index 67edcda..9e5861e 100644
--- a/content/browser/gpu/gpu_process_host.cc
+++ b/content/browser/gpu/gpu_process_host.cc
@@ -981,7 +981,7 @@ void GpuProcessHost::OnAcceleratedSurfaceBuffersSwapped(
 
   FrameSubscriberMap::iterator it = frame_subscribers_.find(params.surface_id);
   if (it != frame_subscribers_.end() && it->second) {
-    const base::Time present_time = base::Time::Now();
+    const base::TimeTicks present_time = base::TimeTicks::Now();
     scoped_refptr<media::VideoFrame> target_frame;
     RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback copy_callback;
     if (it->second->ShouldCaptureFrame(present_time,
diff --git a/content/browser/renderer_host/compositing_iosurface_mac.mm b/content/browser/renderer_host/compositing_iosurface_mac.mm
index b5759ed..606ffe5 100644
--- a/content/browser/renderer_host/compositing_iosurface_mac.mm
+++ b/content/browser/renderer_host/compositing_iosurface_mac.mm
@@ -469,7 +469,7 @@ bool CompositingIOSurfaceMac::DrawIOSurface(
 
   base::Closure copy_done_callback;
   if (frame_subscriber) {
-    const base::Time present_time = base::Time::Now();
+    const base::TimeTicks present_time = base::TimeTicks::Now();
     scoped_refptr<media::VideoFrame> frame;
     RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback callback;
     if (frame_subscriber->ShouldCaptureFrame(present_time, &frame, &callback)) {
diff --git a/content/browser/renderer_host/media/desktop_capture_device.cc b/content/browser/renderer_host/media/desktop_capture_device.cc
index e82b96f..6d655b9 100644
--- a/content/browser/renderer_host/media/desktop_capture_device.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device.cc
@@ -231,8 +231,8 @@ void DesktopCaptureDevice::Core::OnCaptureCompleted(
     output_data = output_frame_->data();
   }
 
-  client_->OnIncomingCapturedFrame(output_data, output_bytes, base::Time::Now(),
-                                   0, capture_format_);
+  client_->OnIncomingCapturedFrame(
+      output_data, output_bytes, base::TimeTicks::Now(), 0, capture_format_);
 }
 
 void DesktopCaptureDevice::Core::DoAllocateAndStart(
diff --git a/content/browser/renderer_host/media/desktop_capture_device_aura.cc b/content/browser/renderer_host/media/desktop_capture_device_aura.cc
index 15e86f0..3783a2a 100644
--- a/content/browser/renderer_host/media/desktop_capture_device_aura.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device_aura.cc
@@ -128,7 +128,7 @@ class DesktopVideoCaptureMachine
   // Response callback for cc::Layer::RequestCopyOfOutput().
   void DidCopyOutput(
       scoped_refptr<media::VideoFrame> video_frame,
-      base::Time start_time,
+      base::TimeTicks start_time,
       const ThreadSafeCaptureOracle::CaptureFrameCallback& capture_frame_cb,
       scoped_ptr<cc::CopyOutputResult> result);
 
@@ -255,7 +255,7 @@ void DesktopVideoCaptureMachine::Capture(bool dirty) {
   scoped_refptr<media::VideoFrame> frame;
   ThreadSafeCaptureOracle::CaptureFrameCallback capture_frame_cb;
 
-  const base::Time start_time = base::Time::Now();
+  const base::TimeTicks start_time = base::TimeTicks::Now();
   const VideoCaptureOracle::Event event =
       dirty ? VideoCaptureOracle::kCompositorUpdate
             : VideoCaptureOracle::kTimerPoll;
@@ -275,7 +275,7 @@ void DesktopVideoCaptureMachine::Capture(bool dirty) {
 }
 
 void CopyOutputFinishedForVideo(
-    base::Time start_time,
+    base::TimeTicks start_time,
     const ThreadSafeCaptureOracle::CaptureFrameCallback& capture_frame_cb,
     const scoped_refptr<media::VideoFrame>& target,
     const SkBitmap& cursor_bitmap,
@@ -290,7 +290,7 @@ void CopyOutputFinishedForVideo(
 
 void DesktopVideoCaptureMachine::DidCopyOutput(
     scoped_refptr<media::VideoFrame> video_frame,
-    base::Time start_time,
+    base::TimeTicks start_time,
     const ThreadSafeCaptureOracle::CaptureFrameCallback& capture_frame_cb,
     scoped_ptr<cc::CopyOutputResult> result) {
   if (result->IsEmpty() || result->size().IsEmpty() || !desktop_layer_)
diff --git a/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc b/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc
index 8ad1495..d581817 100644
--- a/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc
@@ -36,14 +36,14 @@ class MockDeviceClient : public media::VideoCaptureDevice::Client {
   MOCK_METHOD5(OnIncomingCapturedFrame,
                void(const uint8* data,
                     int length,
-                    base::Time timestamp,
+                    base::TimeTicks timestamp,
                     int rotation,
                     const media::VideoCaptureFormat& frame_format));
   MOCK_METHOD5(OnIncomingCapturedBuffer,
                void(const scoped_refptr<Buffer>& buffer,
                     media::VideoFrame::Format format,
                     const gfx::Size& dimensions,
-                    base::Time timestamp,
+                    base::TimeTicks timestamp,
                     int frame_rate));
 };
 
diff --git a/content/browser/renderer_host/media/desktop_capture_device_unittest.cc b/content/browser/renderer_host/media/desktop_capture_device_unittest.cc
index 03dbd53..9ae5469 100644
--- a/content/browser/renderer_host/media/desktop_capture_device_unittest.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device_unittest.cc
@@ -47,14 +47,14 @@ class MockDeviceClient : public media::VideoCaptureDevice::Client {
   MOCK_METHOD5(OnIncomingCapturedFrame,
                void(const uint8* data,
                     int length,
-                    base::Time timestamp,
+                    base::TimeTicks timestamp,
                     int rotation,
                     const media::VideoCaptureFormat& frame_format));
   MOCK_METHOD5(OnIncomingCapturedBuffer,
                void(const scoped_refptr<Buffer>& buffer,
                     media::VideoFrame::Format format,
                     const gfx::Size& dimensions,
-                    base::Time timestamp,
+                    base::TimeTicks timestamp,
                     int frame_rate));
 };
 
diff --git a/content/browser/renderer_host/media/video_capture_controller.cc b/content/browser/renderer_host/media/video_capture_controller.cc
index 88fd72a..f23f50f 100644
--- a/content/browser/renderer_host/media/video_capture_controller.cc
+++ b/content/browser/renderer_host/media/video_capture_controller.cc
@@ -112,14 +112,14 @@ class VideoCaptureController::VideoCaptureDeviceClient
       const gfx::Size& size) OVERRIDE;
   virtual void OnIncomingCapturedFrame(const uint8* data,
                                        int length,
-                                       base::Time timestamp,
+                                       base::TimeTicks timestamp,
                                        int rotation,
                                        const VideoCaptureFormat& frame_format)
       OVERRIDE;
   virtual void OnIncomingCapturedBuffer(const scoped_refptr<Buffer>& buffer,
                                         media::VideoFrame::Format format,
                                         const gfx::Size& dimensions,
-                                        base::Time timestamp,
+                                        base::TimeTicks timestamp,
                                         int frame_rate) OVERRIDE;
   virtual void OnError() OVERRIDE;
 
@@ -267,7 +267,7 @@ VideoCaptureController::VideoCaptureDeviceClient::ReserveOutputBuffer(
 void VideoCaptureController::VideoCaptureDeviceClient::OnIncomingCapturedFrame(
     const uint8* data,
     int length,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     int rotation,
     const VideoCaptureFormat& frame_format) {
   TRACE_EVENT0("video", "VideoCaptureController::OnIncomingCapturedFrame");
@@ -410,7 +410,7 @@ void VideoCaptureController::VideoCaptureDeviceClient::OnIncomingCapturedBuffer(
     const scoped_refptr<Buffer>& buffer,
     media::VideoFrame::Format format,
     const gfx::Size& dimensions,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     int frame_rate) {
   // The capture pipeline expects I420 for now.
   DCHECK_EQ(format, media::VideoFrame::I420)
@@ -476,7 +476,7 @@ void VideoCaptureController::DoIncomingCapturedI420BufferOnIOThread(
     scoped_refptr<media::VideoCaptureDevice::Client::Buffer> buffer,
     const gfx::Size& dimensions,
     int frame_rate,
-    base::Time timestamp) {
+    base::TimeTicks timestamp) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK_NE(buffer->id(), VideoCaptureBufferPool::kInvalidId);
 
diff --git a/content/browser/renderer_host/media/video_capture_controller.h b/content/browser/renderer_host/media/video_capture_controller.h
index 8658cde..9eed94d 100644
--- a/content/browser/renderer_host/media/video_capture_controller.h
+++ b/content/browser/renderer_host/media/video_capture_controller.h
@@ -117,7 +117,7 @@ class CONTENT_EXPORT VideoCaptureController {
       scoped_refptr<media::VideoCaptureDevice::Client::Buffer> buffer,
       const gfx::Size& dimensions,
       int frame_rate,
-      base::Time timestamp);
+      base::TimeTicks timestamp);
   void DoErrorOnIOThread();
   void DoDeviceStoppedOnIOThread();
   void DoBufferDestroyedOnIOThread(int buffer_id_to_drop);
diff --git a/content/browser/renderer_host/media/video_capture_controller_event_handler.h b/content/browser/renderer_host/media/video_capture_controller_event_handler.h
index 6559a53..7eecc09 100644
--- a/content/browser/renderer_host/media/video_capture_controller_event_handler.h
+++ b/content/browser/renderer_host/media/video_capture_controller_event_handler.h
@@ -41,11 +41,10 @@ class CONTENT_EXPORT VideoCaptureControllerEventHandler {
                                  int buffer_id) = 0;
 
   // A buffer has been filled with I420 video.
-  virtual void OnBufferReady(
-      const VideoCaptureControllerID& id,
-      int buffer_id,
-      base::Time timestamp,
-      const media::VideoCaptureFormat& format) = 0;
+  virtual void OnBufferReady(const VideoCaptureControllerID& id,
+                             int buffer_id,
+                             base::TimeTicks timestamp,
+                             const media::VideoCaptureFormat& format) = 0;
 
   // The capture session has ended and no more frames will be sent.
   virtual void OnEnded(const VideoCaptureControllerID& id) = 0;
diff --git a/content/browser/renderer_host/media/video_capture_controller_unittest.cc b/content/browser/renderer_host/media/video_capture_controller_unittest.cc
index 20cc4e4..1852a71 100644
--- a/content/browser/renderer_host/media/video_capture_controller_unittest.cc
+++ b/content/browser/renderer_host/media/video_capture_controller_unittest.cc
@@ -59,7 +59,7 @@ class MockVideoCaptureControllerEventHandler
   }
   virtual void OnBufferReady(const VideoCaptureControllerID& id,
                              int buffer_id,
-                             base::Time timestamp,
+                             base::TimeTicks timestamp,
                              const media::VideoCaptureFormat& format) OVERRIDE {
     DoBufferReady(id);
     base::MessageLoop::current()->PostTask(FROM_HERE,
@@ -279,7 +279,7 @@ TEST_F(VideoCaptureControllerTest, NormalCaptureMultipleClients) {
   device_->OnIncomingCapturedBuffer(buffer,
                                     media::VideoFrame::I420,
                                     capture_resolution,
-                                    base::Time(),
+                                    base::TimeTicks(),
                                     device_format.frame_rate);
   buffer = NULL;
 
@@ -297,7 +297,7 @@ TEST_F(VideoCaptureControllerTest, NormalCaptureMultipleClients) {
   device_->OnIncomingCapturedBuffer(buffer,
                                     media::VideoFrame::I420,
                                     capture_resolution,
-                                    base::Time(),
+                                    base::TimeTicks(),
                                     device_format.frame_rate);
   buffer = NULL;
 
@@ -326,7 +326,7 @@ TEST_F(VideoCaptureControllerTest, NormalCaptureMultipleClients) {
     device_->OnIncomingCapturedBuffer(buffer,
                                       media::VideoFrame::I420,
                                       capture_resolution,
-                                      base::Time(),
+                                      base::TimeTicks(),
                                       device_format.frame_rate);
     buffer = NULL;
   }
@@ -364,7 +364,7 @@ TEST_F(VideoCaptureControllerTest, NormalCaptureMultipleClients) {
   device_->OnIncomingCapturedBuffer(buffer,
                                     media::VideoFrame::I420,
                                     capture_resolution,
-                                    base::Time(),
+                                    base::TimeTicks(),
                                     device_format.frame_rate);
   buffer = NULL;
   buffer =
@@ -380,7 +380,7 @@ TEST_F(VideoCaptureControllerTest, NormalCaptureMultipleClients) {
   device_->OnIncomingCapturedBuffer(buffer,
                                     media::VideoFrame::I420,
                                     capture_resolution,
-                                    base::Time(),
+                                    base::TimeTicks(),
                                     device_format.frame_rate);
   buffer = NULL;
   // B2 is the only client left, and is the only one that should
@@ -424,8 +424,11 @@ TEST_F(VideoCaptureControllerTest, ErrorBeforeDeviceCreation) {
       device_->ReserveOutputBuffer(media::VideoFrame::I420, capture_resolution);
   ASSERT_TRUE(buffer);
 
-  device_->OnIncomingCapturedBuffer(
-      buffer, media::VideoFrame::I420, capture_resolution, base::Time(), 30);
+  device_->OnIncomingCapturedBuffer(buffer,
+                                    media::VideoFrame::I420,
+                                    capture_resolution,
+                                    base::TimeTicks(),
+                                    30);
   buffer = NULL;
 
   base::RunLoop().RunUntilIdle();
@@ -463,7 +466,7 @@ TEST_F(VideoCaptureControllerTest, ErrorAfterDeviceCreation) {
   device_->OnIncomingCapturedBuffer(buffer,
                                     media::VideoFrame::I420,
                                     dims,
-                                    base::Time(),
+                                    base::TimeTicks(),
                                     device_format.frame_rate);
   buffer = NULL;
 
diff --git a/content/browser/renderer_host/media/video_capture_device_impl.cc b/content/browser/renderer_host/media/video_capture_device_impl.cc
index 9b37b29..3a94d50 100644
--- a/content/browser/renderer_host/media/video_capture_device_impl.cc
+++ b/content/browser/renderer_host/media/video_capture_device_impl.cc
@@ -62,7 +62,7 @@ ThreadSafeCaptureOracle::~ThreadSafeCaptureOracle() {}
 
 bool ThreadSafeCaptureOracle::ObserveEventAndDecideCapture(
     VideoCaptureOracle::Event event,
-    base::Time event_time,
+    base::TimeTicks event_time,
     scoped_refptr<media::VideoFrame>* storage,
     CaptureFrameCallback* callback) {
   base::AutoLock guard(lock_);
@@ -166,7 +166,7 @@ void ThreadSafeCaptureOracle::ReportError() {
 void ThreadSafeCaptureOracle::DidCaptureFrame(
     scoped_refptr<media::VideoCaptureDevice::Client::Buffer> buffer,
     int frame_number,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     bool success) {
   base::AutoLock guard(lock_);
   TRACE_EVENT_ASYNC_END2("mirroring", "Capture", buffer.get(),
diff --git a/content/browser/renderer_host/media/video_capture_device_impl.h b/content/browser/renderer_host/media/video_capture_device_impl.h
index d9329b6..d2c03f5 100644
--- a/content/browser/renderer_host/media/video_capture_device_impl.h
+++ b/content/browser/renderer_host/media/video_capture_device_impl.h
@@ -51,11 +51,11 @@ class ThreadSafeCaptureOracle
   // If |success| is true then the frame provided is valid and |timestamp|
   // indicates when the frame was painted.
   // If |success| is false, both the frame provided and |timestamp| are invalid.
-  typedef base::Callback<void(base::Time timestamp, bool success)>
+  typedef base::Callback<void(base::TimeTicks timestamp, bool success)>
       CaptureFrameCallback;
 
   bool ObserveEventAndDecideCapture(VideoCaptureOracle::Event event,
-                                    base::Time event_time,
+                                    base::TimeTicks event_time,
                                     scoped_refptr<media::VideoFrame>* storage,
                                     CaptureFrameCallback* callback);
 
@@ -81,7 +81,7 @@ class ThreadSafeCaptureOracle
   void DidCaptureFrame(
       scoped_refptr<media::VideoCaptureDevice::Client::Buffer> buffer,
       int frame_number,
-      base::Time timestamp,
+      base::TimeTicks timestamp,
       bool success);
   // Protects everything below it.
   base::Lock lock_;
diff --git a/content/browser/renderer_host/media/video_capture_host.cc b/content/browser/renderer_host/media/video_capture_host.cc
index 039d981..292ecb7 100644
--- a/content/browser/renderer_host/media/video_capture_host.cc
+++ b/content/browser/renderer_host/media/video_capture_host.cc
@@ -69,7 +69,7 @@ void VideoCaptureHost::OnBufferDestroyed(
 void VideoCaptureHost::OnBufferReady(
     const VideoCaptureControllerID& controller_id,
     int buffer_id,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     const media::VideoCaptureFormat& frame_format) {
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
@@ -112,7 +112,8 @@ void VideoCaptureHost::DoSendFreeBufferOnIOThread(
 
 void VideoCaptureHost::DoSendFilledBufferOnIOThread(
     const VideoCaptureControllerID& controller_id,
-    int buffer_id, base::Time timestamp,
+    int buffer_id,
+    base::TimeTicks timestamp,
     const media::VideoCaptureFormat& format) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
diff --git a/content/browser/renderer_host/media/video_capture_host.h b/content/browser/renderer_host/media/video_capture_host.h
index b71aac37..bd1db0a 100644
--- a/content/browser/renderer_host/media/video_capture_host.h
+++ b/content/browser/renderer_host/media/video_capture_host.h
@@ -84,11 +84,10 @@ class CONTENT_EXPORT VideoCaptureHost
                                int buffer_id) OVERRIDE;
   virtual void OnBufferDestroyed(const VideoCaptureControllerID& id,
                                  int buffer_id) OVERRIDE;
-  virtual void OnBufferReady(
-      const VideoCaptureControllerID& id,
-      int buffer_id,
-      base::Time timestamp,
-      const media::VideoCaptureFormat& format) OVERRIDE;
+  virtual void OnBufferReady(const VideoCaptureControllerID& id,
+                             int buffer_id,
+                             base::TimeTicks timestamp,
+                             const media::VideoCaptureFormat& format) OVERRIDE;
   virtual void OnEnded(const VideoCaptureControllerID& id) OVERRIDE;
 
  private:
@@ -138,7 +137,7 @@ class CONTENT_EXPORT VideoCaptureHost
   void DoSendFilledBufferOnIOThread(
       const VideoCaptureControllerID& controller_id,
       int buffer_id,
-      base::Time timestamp,
+      base::TimeTicks timestamp,
       const media::VideoCaptureFormat& format);
 
   // Handle error coming from VideoCaptureDevice.
diff --git a/content/browser/renderer_host/media/video_capture_host_unittest.cc b/content/browser/renderer_host/media/video_capture_host_unittest.cc
index 551b0c2..01545db 100644
--- a/content/browser/renderer_host/media/video_capture_host_unittest.cc
+++ b/content/browser/renderer_host/media/video_capture_host_unittest.cc
@@ -119,7 +119,9 @@ class MockVideoCaptureHost : public VideoCaptureHost {
   MOCK_METHOD2(OnBufferFreed,
                void(int device_id, int buffer_id));
   MOCK_METHOD4(OnBufferFilled,
-               void(int device_id, int buffer_id, base::Time timestamp,
+               void(int device_id,
+                    int buffer_id,
+                    base::TimeTicks timestamp,
                     const media::VideoCaptureFormat& format));
   MOCK_METHOD2(OnStateChanged, void(int device_id, VideoCaptureState state));
 
@@ -203,7 +205,7 @@ class MockVideoCaptureHost : public VideoCaptureHost {
 
   void OnBufferFilledDispatch(int device_id,
                               int buffer_id,
-                              base::Time timestamp,
+                              base::TimeTicks timestamp,
                               const media::VideoCaptureFormat& frame_format) {
     base::SharedMemory* dib = filled_dib_[buffer_id];
     ASSERT_TRUE(dib != NULL);
diff --git a/content/browser/renderer_host/media/video_capture_manager_unittest.cc b/content/browser/renderer_host/media/video_capture_manager_unittest.cc
index bc89159..1dfad2d 100644
--- a/content/browser/renderer_host/media/video_capture_manager_unittest.cc
+++ b/content/browser/renderer_host/media/video_capture_manager_unittest.cc
@@ -53,11 +53,11 @@ class MockFrameObserver : public VideoCaptureControllerEventHandler {
                                int length, int buffer_id) OVERRIDE {}
   virtual void OnBufferDestroyed(const VideoCaptureControllerID& id,
                                int buffer_id) OVERRIDE {}
-  virtual void OnBufferReady(
-      const VideoCaptureControllerID& id,
-      int buffer_id,
-      base::Time timestamp,
-      const media::VideoCaptureFormat& format) OVERRIDE {}
+  virtual void OnBufferReady(const VideoCaptureControllerID& id,
+                             int buffer_id,
+                             base::TimeTicks timestamp,
+                             const media::VideoCaptureFormat& format)
+      OVERRIDE {}
   virtual void OnEnded(const VideoCaptureControllerID& id) OVERRIDE {}
 
   void OnGotControllerCallback(VideoCaptureControllerID) {}
diff --git a/content/browser/renderer_host/media/video_capture_oracle.cc b/content/browser/renderer_host/media/video_capture_oracle.cc
index fb41ec2..499bde4 100644
--- a/content/browser/renderer_host/media/video_capture_oracle.cc
+++ b/content/browser/renderer_host/media/video_capture_oracle.cc
@@ -33,8 +33,8 @@ VideoCaptureOracle::VideoCaptureOracle(base::TimeDelta capture_period,
                kNumRedundantCapturesOfStaticContent) {}
 
 bool VideoCaptureOracle::ObserveEventAndDecideCapture(
-      Event event,
-      base::Time event_time) {
+    Event event,
+    base::TimeTicks event_time) {
   // Record |event| and decide whether it's a good time to capture.
   const bool content_is_dirty = (event == kCompositorUpdate ||
                                  event == kSoftwarePaint);
@@ -54,7 +54,7 @@ int VideoCaptureOracle::RecordCapture() {
 }
 
 bool VideoCaptureOracle::CompleteCapture(int frame_number,
-                                         base::Time timestamp) {
+                                         base::TimeTicks timestamp) {
   // Drop frame if previous frame number is higher or we're trying to deliver
   // a frame with the same timestamp.
   if (last_delivered_frame_number_ > frame_number ||
@@ -88,7 +88,8 @@ SmoothEventSampler::SmoothEventSampler(base::TimeDelta capture_period,
   DCHECK_GT(capture_period_.InMicroseconds(), 0);
 }
 
-bool SmoothEventSampler::AddEventAndConsiderSampling(base::Time event_time) {
+bool SmoothEventSampler::AddEventAndConsiderSampling(
+    base::TimeTicks event_time) {
   DCHECK(!event_time.is_null());
 
   // Add tokens to the bucket based on advancement in time.  Then, re-bound the
@@ -137,7 +138,8 @@ void SmoothEventSampler::RecordSample() {
       << "Content changed; capture will resume.";
 }
 
-bool SmoothEventSampler::IsOverdueForSamplingAt(base::Time event_time) const {
+bool SmoothEventSampler::IsOverdueForSamplingAt(base::TimeTicks event_time)
+    const {
   DCHECK(!event_time.is_null());
 
   // If we don't get events on compositor updates on this platform, then we
@@ -149,6 +151,9 @@ bool SmoothEventSampler::IsOverdueForSamplingAt(base::Time event_time) const {
     }
   }
 
+  if (last_sample_.is_null())
+    return true;
+
   // If we're dirty but not yet old, then we've recently gotten updates, so we
   // won't request a sample just yet.
   base::TimeDelta dirty_interval = event_time - last_sample_;
diff --git a/content/browser/renderer_host/media/video_capture_oracle.h b/content/browser/renderer_host/media/video_capture_oracle.h
index 739b569..c14d16f 100644
--- a/content/browser/renderer_host/media/video_capture_oracle.h
+++ b/content/browser/renderer_host/media/video_capture_oracle.h
@@ -22,7 +22,7 @@ class CONTENT_EXPORT SmoothEventSampler {
   // Add a new event to the event history, and return whether it ought to be
   // sampled based on the desired |capture_period|. The event is not recorded as
   // a sample until RecordSample() is called.
-  bool AddEventAndConsiderSampling(base::Time event_time);
+  bool AddEventAndConsiderSampling(base::TimeTicks event_time);
 
   // Operates on the last event added by AddEventAndConsiderSampling(), marking
   // it as sampled. After this point we are current in the stream of events, as
@@ -31,7 +31,7 @@ class CONTENT_EXPORT SmoothEventSampler {
 
   // Returns true if, at time |event_time|, sampling should occur because too
   // much time will have passed relative to the last event and/or sample.
-  bool IsOverdueForSamplingAt(base::Time event_time) const;
+  bool IsOverdueForSamplingAt(base::TimeTicks event_time) const;
 
   // Returns true if AddEventAndConsiderSampling() has been called since the
   // last call to RecordSample().
@@ -43,8 +43,8 @@ class CONTENT_EXPORT SmoothEventSampler {
   const int redundant_capture_goal_;
   const base::TimeDelta token_bucket_capacity_;
 
-  base::Time current_event_;
-  base::Time last_sample_;
+  base::TimeTicks current_event_;
+  base::TimeTicks last_sample_;
   int overdue_sample_count_;
   base::TimeDelta token_bucket_;
 
@@ -70,9 +70,7 @@ class CONTENT_EXPORT VideoCaptureOracle {
   // Record an event of type |event|, and decide whether the caller should do a
   // frame capture immediately. Decisions of the oracle are final: the caller
   // must do what it is told.
-  bool ObserveEventAndDecideCapture(
-      Event event,
-      base::Time event_time);
+  bool ObserveEventAndDecideCapture(Event event, base::TimeTicks event_time);
 
   // Record the start of a capture.  Returns a frame_number to be used with
   // CompleteCapture().
@@ -80,7 +78,7 @@ class CONTENT_EXPORT VideoCaptureOracle {
 
   // Record the completion of a capture.  Returns true iff the captured frame
   // should be delivered.
-  bool CompleteCapture(int frame_number, base::Time timestamp);
+  bool CompleteCapture(int frame_number, base::TimeTicks timestamp);
 
   base::TimeDelta capture_period() const { return capture_period_; }
 
@@ -96,7 +94,7 @@ class CONTENT_EXPORT VideoCaptureOracle {
   int last_delivered_frame_number_;
 
   // Stores the timestamp of the last delivered frame.
-  base::Time last_delivered_frame_timestamp_;
+  base::TimeTicks last_delivered_frame_timestamp_;
 
   // Tracks present/paint history.
   SmoothEventSampler sampler_;
diff --git a/content/browser/renderer_host/media/video_capture_oracle_unittest.cc b/content/browser/renderer_host/media/video_capture_oracle_unittest.cc
index 40c1826..22e2dda 100644
--- a/content/browser/renderer_host/media/video_capture_oracle_unittest.cc
+++ b/content/browser/renderer_host/media/video_capture_oracle_unittest.cc
@@ -12,7 +12,8 @@ namespace content {
 namespace {
 
 void SteadyStateSampleAndAdvance(base::TimeDelta vsync,
-                                 SmoothEventSampler* sampler, base::Time* t) {
+                                 SmoothEventSampler* sampler,
+                                 base::TimeTicks* t) {
   ASSERT_TRUE(sampler->AddEventAndConsiderSampling(*t));
   ASSERT_TRUE(sampler->HasUnrecordedEvent());
   sampler->RecordSample();
@@ -23,7 +24,8 @@ void SteadyStateSampleAndAdvance(base::TimeDelta vsync,
 }
 
 void SteadyStateNoSampleAndAdvance(base::TimeDelta vsync,
-                                   SmoothEventSampler* sampler, base::Time* t) {
+                                   SmoothEventSampler* sampler,
+                                   base::TimeTicks* t) {
   ASSERT_FALSE(sampler->AddEventAndConsiderSampling(*t));
   ASSERT_TRUE(sampler->HasUnrecordedEvent());
   ASSERT_FALSE(sampler->IsOverdueForSamplingAt(*t));
@@ -31,9 +33,16 @@ void SteadyStateNoSampleAndAdvance(base::TimeDelta vsync,
   ASSERT_FALSE(sampler->IsOverdueForSamplingAt(*t));
 }
 
+void TimeTicksFromString(const char* string, base::TimeTicks* t) {
+  base::Time time;
+  ASSERT_TRUE(base::Time::FromString(string, &time));
+  *t = base::TimeTicks::UnixEpoch() + (time - base::Time::UnixEpoch());
+}
+
 void TestRedundantCaptureStrategy(base::TimeDelta capture_period,
                                   int redundant_capture_goal,
-                                  SmoothEventSampler* sampler, base::Time* t) {
+                                  SmoothEventSampler* sampler,
+                                  base::TimeTicks* t) {
   // Before any events have been considered, we're overdue for sampling.
   ASSERT_TRUE(sampler->IsOverdueForSamplingAt(*t));
 
@@ -68,8 +77,8 @@ TEST(SmoothEventSamplerTest, Sample60HertzAt30Hertz) {
   const base::TimeDelta vsync = base::TimeDelta::FromSeconds(1) / 60;
 
   SmoothEventSampler sampler(capture_period, true, redundant_capture_goal);
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
 
   TestRedundantCaptureStrategy(capture_period, redundant_capture_goal,
                                &sampler, &t);
@@ -108,8 +117,8 @@ TEST(SmoothEventSamplerTest, Sample50HertzAt30Hertz) {
   const base::TimeDelta vsync = base::TimeDelta::FromSeconds(1) / 50;
 
   SmoothEventSampler sampler(capture_period, true, redundant_capture_goal);
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
 
   TestRedundantCaptureStrategy(capture_period, redundant_capture_goal,
                                &sampler, &t);
@@ -154,8 +163,8 @@ TEST(SmoothEventSamplerTest, Sample75HertzAt30Hertz) {
   const base::TimeDelta vsync = base::TimeDelta::FromSeconds(1) / 75;
 
   SmoothEventSampler sampler(capture_period, true, redundant_capture_goal);
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
 
   TestRedundantCaptureStrategy(capture_period, redundant_capture_goal,
                                &sampler, &t);
@@ -204,8 +213,8 @@ TEST(SmoothEventSamplerTest, Sample30HertzAt30Hertz) {
   const base::TimeDelta vsync = base::TimeDelta::FromSeconds(1) / 30;
 
   SmoothEventSampler sampler(capture_period, true, redundant_capture_goal);
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
 
   TestRedundantCaptureStrategy(capture_period, redundant_capture_goal,
                                &sampler, &t);
@@ -240,8 +249,8 @@ TEST(SmoothEventSamplerTest, Sample24HertzAt30Hertz) {
   const base::TimeDelta vsync = base::TimeDelta::FromSeconds(1) / 24;
 
   SmoothEventSampler sampler(capture_period, true, redundant_capture_goal);
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
 
   TestRedundantCaptureStrategy(capture_period, redundant_capture_goal,
                                &sampler, &t);
@@ -274,8 +283,8 @@ TEST(SmoothEventSamplerTest, DoubleDrawAtOneTimeStillDirties) {
   const base::TimeDelta overdue_period = base::TimeDelta::FromSeconds(1);
 
   SmoothEventSampler sampler(capture_period, true, 1);
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
 
   ASSERT_TRUE(sampler.AddEventAndConsiderSampling(t));
   sampler.RecordSample();
@@ -299,8 +308,8 @@ TEST(SmoothEventSamplerTest, FallbackToPollingIfUpdatesUnreliable) {
 
   SmoothEventSampler should_not_poll(timer_interval, true, 1);
   SmoothEventSampler should_poll(timer_interval, false, 1);
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
 
   // Do one round of the "happy case" where an event was received and
   // RecordSample() was called by the client.
@@ -355,8 +364,8 @@ struct DataPoint {
 void ReplayCheckingSamplerDecisions(const DataPoint* data_points,
                                     size_t num_data_points,
                                     SmoothEventSampler* sampler) {
-  base::Time t;
-  ASSERT_TRUE(base::Time::FromString("Sat, 23 Mar 2013 1:21:08 GMT", &t));
+  base::TimeTicks t;
+  TimeTicksFromString("Sat, 23 Mar 2013 1:21:08 GMT", &t);
   for (size_t i = 0; i < num_data_points; ++i) {
     t += base::TimeDelta::FromMicroseconds(
         static_cast<int64>(data_points[i].increment_ms * 1000));
diff --git a/content/browser/renderer_host/media/web_contents_video_capture_device.cc b/content/browser/renderer_host/media/web_contents_video_capture_device.cc
index 15258a0..4f21539 100644
--- a/content/browser/renderer_host/media/web_contents_video_capture_device.cc
+++ b/content/browser/renderer_host/media/web_contents_video_capture_device.cc
@@ -103,7 +103,7 @@ gfx::Rect ComputeYV12LetterboxRegion(const gfx::Size& frame_size,
 // compatible with RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback.
 void InvokeCaptureFrameCallback(
     const ThreadSafeCaptureOracle::CaptureFrameCallback& capture_frame_cb,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     bool frame_captured) {
   capture_frame_cb.Run(timestamp, frame_captured);
 }
@@ -118,7 +118,7 @@ class FrameSubscriber : public RenderWidgetHostViewFrameSubscriber {
         oracle_proxy_(oracle) {}
 
   virtual bool ShouldCaptureFrame(
-      base::Time present_time,
+      base::TimeTicks present_time,
       scoped_refptr<media::VideoFrame>* storage,
       RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback*
           deliver_frame_cb) OVERRIDE;
@@ -145,11 +145,11 @@ class FrameSubscriber : public RenderWidgetHostViewFrameSubscriber {
 // autonomously on some other thread.
 class ContentCaptureSubscription : public content::NotificationObserver {
  public:
-  typedef base::Callback<void(
-      const base::Time&,
-      const scoped_refptr<media::VideoFrame>&,
-      const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&)>
-          CaptureCallback;
+  typedef base::Callback<
+      void(const base::TimeTicks&,
+           const scoped_refptr<media::VideoFrame>&,
+           const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&)>
+      CaptureCallback;
 
   // Create a subscription. Whenever a manual capture is required, the
   // subscription will invoke |capture_callback| on the UI thread to do the
@@ -218,11 +218,10 @@ class WebContentsCaptureMachine
   // completes. The copy will occur to |target|.
   //
   // This may be used as a ContentCaptureSubscription::CaptureCallback.
-  void Capture(
-      const base::Time& start_time,
-      const scoped_refptr<media::VideoFrame>& target,
-      const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
-          deliver_frame_cb);
+  void Capture(const base::TimeTicks& start_time,
+               const scoped_refptr<media::VideoFrame>& target,
+               const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
+                   deliver_frame_cb);
 
   // content::WebContentsObserver implementation.
   virtual void DidShowFullscreenWidget(int routing_id) OVERRIDE {
@@ -261,7 +260,7 @@ class WebContentsCaptureMachine
 
   // Response callback for RenderWidgetHost::CopyFromBackingStore().
   void DidCopyFromBackingStore(
-      const base::Time& start_time,
+      const base::TimeTicks& start_time,
       const scoped_refptr<media::VideoFrame>& target,
       const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
           deliver_frame_cb,
@@ -270,7 +269,7 @@ class WebContentsCaptureMachine
 
   // Response callback for RWHVP::CopyFromCompositingSurfaceToVideoFrame().
   void DidCopyFromCompositingSurfaceToVideoFrame(
-      const base::Time& start_time,
+      const base::TimeTicks& start_time,
       const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
           deliver_frame_cb,
       bool success);
@@ -318,7 +317,7 @@ class VideoFrameDeliveryLog {
  private:
   // The following keep track of and log the effective frame rate whenever
   // verbose logging is turned on.
-  base::Time last_frame_rate_log_time_;
+  base::TimeTicks last_frame_rate_log_time_;
   int count_frames_rendered_;
   int last_frame_number_;
 
@@ -326,7 +325,7 @@ class VideoFrameDeliveryLog {
 };
 
 bool FrameSubscriber::ShouldCaptureFrame(
-    base::Time present_time,
+    base::TimeTicks present_time,
     scoped_refptr<media::VideoFrame>* storage,
     DeliverFrameCallback* deliver_frame_cb) {
   TRACE_EVENT1("mirroring", "FrameSubscriber::ShouldCaptureFrame",
@@ -413,7 +412,7 @@ void ContentCaptureSubscription::Observe(
   base::Closure copy_done_callback;
   scoped_refptr<media::VideoFrame> frame;
   RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback deliver_frame_cb;
-  const base::Time start_time = base::Time::Now();
+  const base::TimeTicks start_time = base::TimeTicks::Now();
   if (paint_subscriber_.ShouldCaptureFrame(start_time,
                                            &frame,
                                            &deliver_frame_cb)) {
@@ -432,7 +431,7 @@ void ContentCaptureSubscription::OnTimer() {
   scoped_refptr<media::VideoFrame> frame;
   RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback deliver_frame_cb;
 
-  const base::Time start_time = base::Time::Now();
+  const base::TimeTicks start_time = base::TimeTicks::Now();
   if (timer_subscriber_.ShouldCaptureFrame(start_time,
                                            &frame,
                                            &deliver_frame_cb)) {
@@ -519,7 +518,7 @@ void VideoFrameDeliveryLog::ChronicleFrameDelivery(int frame_number) {
   // Log frame rate, if verbose logging is turned on.
   static const base::TimeDelta kFrameRateLogInterval =
       base::TimeDelta::FromSeconds(10);
-  const base::Time now = base::Time::Now();
+  const base::TimeTicks now = base::TimeTicks::Now();
   if (last_frame_rate_log_time_.is_null()) {
     last_frame_rate_log_time_ = now;
     count_frames_rendered_ = 0;
@@ -589,7 +588,7 @@ void WebContentsCaptureMachine::Stop() {
 }
 
 void WebContentsCaptureMachine::Capture(
-    const base::Time& start_time,
+    const base::TimeTicks& start_time,
     const scoped_refptr<media::VideoFrame>& target,
     const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
         deliver_frame_cb) {
@@ -599,7 +598,7 @@ void WebContentsCaptureMachine::Capture(
   RenderWidgetHostViewPort* view =
       rwh ? RenderWidgetHostViewPort::FromRWHV(rwh->GetView()) : NULL;
   if (!view || !rwh) {
-    deliver_frame_cb.Run(base::Time(), false);
+    deliver_frame_cb.Run(base::TimeTicks(), false);
     return;
   }
 
@@ -698,7 +697,7 @@ RenderWidgetHost* WebContentsCaptureMachine::GetTarget() {
 }
 
 void WebContentsCaptureMachine::DidCopyFromBackingStore(
-    const base::Time& start_time,
+    const base::TimeTicks& start_time,
     const scoped_refptr<media::VideoFrame>& target,
     const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
         deliver_frame_cb,
@@ -706,7 +705,7 @@ void WebContentsCaptureMachine::DidCopyFromBackingStore(
     const SkBitmap& bitmap) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  base::Time now = base::Time::Now();
+  base::TimeTicks now = base::TimeTicks::Now();
   if (success) {
     UMA_HISTOGRAM_TIMES("TabCapture.CopyTimeBitmap", now - start_time);
     TRACE_EVENT_ASYNC_STEP_INTO0("mirroring", "Capture", target.get(),
@@ -722,12 +721,12 @@ void WebContentsCaptureMachine::DidCopyFromBackingStore(
 }
 
 void WebContentsCaptureMachine::DidCopyFromCompositingSurfaceToVideoFrame(
-    const base::Time& start_time,
+    const base::TimeTicks& start_time,
     const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
         deliver_frame_cb,
     bool success) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  base::Time now = base::Time::Now();
+  base::TimeTicks now = base::TimeTicks::Now();
 
   if (success) {
     UMA_HISTOGRAM_TIMES("TabCapture.CopyTimeVideoFrame", now - start_time);
diff --git a/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc b/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc
index 6abb183..39b427b 100644
--- a/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc
+++ b/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc
@@ -192,7 +192,7 @@ class CaptureTestView : public TestRenderWidgetHostView {
 
   // Simulate a compositor paint event for our subscriber.
   void SimulateUpdate() {
-    const base::Time present_time = base::Time::Now();
+    const base::TimeTicks present_time = base::TimeTicks::Now();
     RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback callback;
     scoped_refptr<media::VideoFrame> target;
     if (subscriber_ && subscriber_->ShouldCaptureFrame(present_time,
@@ -335,7 +335,7 @@ class StubClient : public media::VideoCaptureDevice::Client {
   virtual void OnIncomingCapturedFrame(
       const uint8* data,
       int length,
-      base::Time timestamp,
+      base::TimeTicks timestamp,
       int rotation,
       const media::VideoCaptureFormat& frame_format) OVERRIDE {
     FAIL();
@@ -344,7 +344,7 @@ class StubClient : public media::VideoCaptureDevice::Client {
   virtual void OnIncomingCapturedBuffer(const scoped_refptr<Buffer>& buffer,
                                         media::VideoFrame::Format format,
                                         const gfx::Size& dimensions,
-                                        base::Time timestamp,
+                                        base::TimeTicks timestamp,
                                         int frame_rate) OVERRIDE {
     EXPECT_EQ(gfx::Size(kTestWidth, kTestHeight), dimensions);
     EXPECT_EQ(media::VideoFrame::I420, format);
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 9a38126..1c54253 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -1297,7 +1297,7 @@ void RenderWidgetHostViewAura::SwapBuffersCompleted(
 
 void RenderWidgetHostViewAura::DidReceiveFrameFromRenderer() {
   if (frame_subscriber() && CanCopyToVideoFrame()) {
-    const base::Time present_time = base::Time::Now();
+    const base::TimeTicks present_time = base::TimeTicks::Now();
     scoped_refptr<media::VideoFrame> frame;
     RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback callback;
     if (frame_subscriber()->ShouldCaptureFrame(present_time,
diff --git a/content/browser/renderer_host/render_widget_host_view_browsertest.cc b/content/browser/renderer_host/render_widget_host_view_browsertest.cc
index 3f1d760..22bc6f2 100644
--- a/content/browser/renderer_host/render_widget_host_view_browsertest.cc
+++ b/content/browser/renderer_host/render_widget_host_view_browsertest.cc
@@ -147,7 +147,7 @@ class RenderWidgetHostViewBrowserTest : public ContentBrowserTest {
   // Callback when using frame subscriber API.
   void FrameDelivered(const scoped_refptr<base::MessageLoopProxy>& loop,
                       base::Closure quit_closure,
-                      base::Time timestamp,
+                      base::TimeTicks timestamp,
                       bool frame_captured) {
     ++callback_invoke_count_;
     if (frame_captured)
@@ -338,10 +338,9 @@ class FakeFrameSubscriber : public RenderWidgetHostViewFrameSubscriber {
       : callback_(callback) {
   }
 
-  virtual bool ShouldCaptureFrame(
-      base::Time present_time,
-      scoped_refptr<media::VideoFrame>* storage,
-      DeliverFrameCallback* callback) OVERRIDE {
+  virtual bool ShouldCaptureFrame(base::TimeTicks present_time,
+                                  scoped_refptr<media::VideoFrame>* storage,
+                                  DeliverFrameCallback* callback) OVERRIDE {
     // Only allow one frame capture to be made.  Otherwise, the compositor could
     // start multiple captures, unbounded, and eventually its own limiter logic
     // will begin invoking |callback| with a |false| result.  This flakes out
@@ -494,14 +493,15 @@ IN_PROC_BROWSER_TEST_P(CompositingRenderWidgetHostViewBrowserTest, CopyTwice) {
                  base::Unretained(this),
                  base::MessageLoopProxy::current(),
                  base::Closure(),
-                 base::Time::Now()));
+                 base::TimeTicks::Now()));
   view->CopyFromCompositingSurfaceToVideoFrame(
-      gfx::Rect(view->GetViewBounds().size()), second_output,
+      gfx::Rect(view->GetViewBounds().size()),
+      second_output,
       base::Bind(&RenderWidgetHostViewBrowserTest::FrameDelivered,
                  base::Unretained(this),
                  base::MessageLoopProxy::current(),
                  run_loop.QuitClosure(),
-                 base::Time::Now()));
+                 base::TimeTicks::Now()));
   run_loop.Run();
 
   EXPECT_EQ(2, callback_invoke_count());
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index d5825c8..43b0086 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1294,7 +1294,7 @@ void RenderWidgetHostViewMac::CompositorSwapBuffers(
     // There is no window to present so capturing during present won't work.
     // We check if frame subscriber wants this frame and capture manually.
     if (compositing_iosurface_ && frame_subscriber_) {
-      const base::Time present_time = base::Time::Now();
+      const base::TimeTicks present_time = base::TimeTicks::Now();
       scoped_refptr<media::VideoFrame> frame;
       RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback callback;
       if (frame_subscriber_->ShouldCaptureFrame(present_time,
diff --git a/content/common/media/video_capture_messages.h b/content/common/media/video_capture_messages.h
index 55cbb38..a1e913f 100644
--- a/content/common/media/video_capture_messages.h
+++ b/content/common/media/video_capture_messages.h
@@ -46,7 +46,7 @@ IPC_MESSAGE_CONTROL2(VideoCaptureMsg_FreeBuffer,
 IPC_MESSAGE_CONTROL4(VideoCaptureMsg_BufferReady,
                      int /* device id */,
                      int /* buffer_id */,
-                     base::Time /* timestamp */,
+                     base::TimeTicks /* timestamp */,
                      media::VideoCaptureFormat /* resolution */)
 
 // Start a video capture as |device_id|, a new id picked by the renderer
diff --git a/content/port/browser/render_widget_host_view_frame_subscriber.h b/content/port/browser/render_widget_host_view_frame_subscriber.h
index c99624f..76fd4b1 100644
--- a/content/port/browser/render_widget_host_view_frame_subscriber.h
+++ b/content/port/browser/render_widget_host_view_frame_subscriber.h
@@ -40,9 +40,8 @@ class RenderWidgetHostViewFrameSubscriber {
   // If |frame_captured| is false then the content in frame provided is
   // invalid. There was an error during the process of frame capture or the
   // platform layer is shutting down. |timestamp| is also invalid in this case.
-  typedef base::Callback<void(
-      base::Time /* timestamp */,
-      bool /* frame_captured */)> DeliverFrameCallback;
+  typedef base::Callback<void(base::TimeTicks /* timestamp */,
+                              bool /* frame_captured */)> DeliverFrameCallback;
 
   // Called when a new frame is going to be presented at time
   // |present_time|. Implementation can decide whether the current frame should
@@ -61,10 +60,9 @@ class RenderWidgetHostViewFrameSubscriber {
   // platform layer to decide when to deliver a captured frame.
   //
   // Return false if the current frame should not be captured.
-  virtual bool ShouldCaptureFrame(
-      base::Time present_time,
-      scoped_refptr<media::VideoFrame>* storage,
-      DeliverFrameCallback* callback) = 0;
+  virtual bool ShouldCaptureFrame(base::TimeTicks present_time,
+                                  scoped_refptr<media::VideoFrame>* storage,
+                                  DeliverFrameCallback* callback) = 0;
 };
 
 }  // namespace content
diff --git a/content/renderer/media/video_capture_impl.cc b/content/renderer/media/video_capture_impl.cc
index 30b43dd..066daf2 100644
--- a/content/renderer/media/video_capture_impl.cc
+++ b/content/renderer/media/video_capture_impl.cc
@@ -104,7 +104,7 @@ void VideoCaptureImpl::OnBufferDestroyed(int buffer_id) {
 
 void VideoCaptureImpl::OnBufferReceived(
     int buffer_id,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     const media::VideoCaptureFormat& format) {
   capture_message_loop_proxy_->PostTask(FROM_HERE,
       base::Bind(&VideoCaptureImpl::DoBufferReceivedOnCaptureThread,
@@ -177,7 +177,7 @@ void VideoCaptureImpl::DoStartCaptureOnCaptureThread(
       }
       DVLOG(1) << "StartCapture: starting with first resolution "
                << params_.requested_format.frame_size.ToString();
-
+      first_frame_timestamp_ = base::TimeTicks();
       StartCaptureInternal();
     }
   }
@@ -242,7 +242,7 @@ void VideoCaptureImpl::DoBufferDestroyedOnCaptureThread(int buffer_id) {
 
 void VideoCaptureImpl::DoBufferReceivedOnCaptureThread(
     int buffer_id,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     const media::VideoCaptureFormat& format) {
   DCHECK(capture_message_loop_proxy_->BelongsToCurrentThread());
 
@@ -252,6 +252,8 @@ void VideoCaptureImpl::DoBufferReceivedOnCaptureThread(
   }
 
   last_frame_format_ = format;
+  if (first_frame_timestamp_.is_null())
+    first_frame_timestamp_ = timestamp;
 
   ClientBufferMap::iterator iter = client_buffers_.find(buffer_id);
   DCHECK(iter != client_buffers_.end());
@@ -265,9 +267,7 @@ void VideoCaptureImpl::DoBufferReceivedOnCaptureThread(
           reinterpret_cast<uint8*>(buffer->buffer->memory()),
           buffer->buffer_size,
           buffer->buffer->handle(),
-          // TODO(sheu): convert VideoCaptureMessageFilter::Delegate to use
-          // base::TimeTicks instead of base::Time.  http://crbug.com/249215
-          timestamp - base::Time::UnixEpoch(),
+          timestamp - first_frame_timestamp_,
           media::BindToLoop(
               capture_message_loop_proxy_,
               base::Bind(
diff --git a/content/renderer/media/video_capture_impl.h b/content/renderer/media/video_capture_impl.h
index 2215cef..55a2eef 100644
--- a/content/renderer/media/video_capture_impl.h
+++ b/content/renderer/media/video_capture_impl.h
@@ -62,10 +62,10 @@ class CONTENT_EXPORT VideoCaptureImpl
                                int length,
                                int buffer_id) OVERRIDE;
   virtual void OnBufferDestroyed(int buffer_id) OVERRIDE;
-  virtual void OnBufferReceived(
-      int buffer_id,
-      base::Time timestamp,
-      const media::VideoCaptureFormat& format) OVERRIDE;
+  virtual void OnBufferReceived(int buffer_id,
+                                base::TimeTicks timestamp,
+                                const media::VideoCaptureFormat& format)
+      OVERRIDE;
   virtual void OnStateChanged(VideoCaptureState state) OVERRIDE;
   virtual void OnDelegateAdded(int32 device_id) OVERRIDE;
 
@@ -94,10 +94,9 @@ class CONTENT_EXPORT VideoCaptureImpl
                                       int length,
                                       int buffer_id);
   void DoBufferDestroyedOnCaptureThread(int buffer_id);
-  void DoBufferReceivedOnCaptureThread(
-      int buffer_id,
-      base::Time timestamp,
-      const media::VideoCaptureFormat& format);
+  void DoBufferReceivedOnCaptureThread(int buffer_id,
+                                       base::TimeTicks timestamp,
+                                       const media::VideoCaptureFormat& format);
   void DoClientBufferFinishedOnCaptureThread(
       int buffer_id,
       const scoped_refptr<ClientBuffer>& buffer);
@@ -141,6 +140,9 @@ class CONTENT_EXPORT VideoCaptureImpl
   // The device's video capture format sent from browser process side.
   media::VideoCaptureFormat last_frame_format_;
 
+  // The device's first captured frame timestamp sent from browser process side.
+  base::TimeTicks first_frame_timestamp_;
+
   bool suspended_;
   VideoCaptureState state_;
 
diff --git a/content/renderer/media/video_capture_message_filter.cc b/content/renderer/media/video_capture_message_filter.cc
index 52847d9..98b2e4e 100644
--- a/content/renderer/media/video_capture_message_filter.cc
+++ b/content/renderer/media/video_capture_message_filter.cc
@@ -117,7 +117,7 @@ void VideoCaptureMessageFilter::OnBufferCreated(
 void VideoCaptureMessageFilter::OnBufferReceived(
     int device_id,
     int buffer_id,
-    base::Time timestamp,
+    base::TimeTicks timestamp,
     const media::VideoCaptureFormat& format) {
   Delegate* delegate = find_delegate(device_id);
   if (!delegate) {
diff --git a/content/renderer/media/video_capture_message_filter.h b/content/renderer/media/video_capture_message_filter.h
index 024c1bd..2c71efa 100644
--- a/content/renderer/media/video_capture_message_filter.h
+++ b/content/renderer/media/video_capture_message_filter.h
@@ -34,7 +34,7 @@ class CONTENT_EXPORT VideoCaptureMessageFilter
 
     // Called when a video frame buffer is received from the browser process.
     virtual void OnBufferReceived(int buffer_id,
-                                  base::Time timestamp,
+                                  base::TimeTicks timestamp,
                                   const media::VideoCaptureFormat& format) = 0;
 
     // Called when state of a video capture device has changed in the browser
@@ -85,7 +85,7 @@ class CONTENT_EXPORT VideoCaptureMessageFilter
   // Receive a filled buffer from browser process.
   void OnBufferReceived(int device_id,
                         int buffer_id,
-                        base::Time timestamp,
+                        base::TimeTicks timestamp,
                         const media::VideoCaptureFormat& format);
 
   // State of browser process' video capture device has changed.
diff --git a/content/renderer/media/video_capture_message_filter_unittest.cc b/content/renderer/media/video_capture_message_filter_unittest.cc
index 366bcb0..985aebe 100644
--- a/content/renderer/media/video_capture_message_filter_unittest.cc
+++ b/content/renderer/media/video_capture_message_filter_unittest.cc
@@ -29,9 +29,10 @@ class MockVideoCaptureDelegate : public VideoCaptureMessageFilter::Delegate {
                                      int length,
                                      int buffer_id));
   MOCK_METHOD1(OnBufferDestroyed, void(int buffer_id));
-  MOCK_METHOD3(OnBufferReceived, void(int buffer_id,
-                                      base::Time timestamp,
-                                      const media::VideoCaptureFormat& format));
+  MOCK_METHOD3(OnBufferReceived,
+               void(int buffer_id,
+                    base::TimeTicks timestamp,
+                    const media::VideoCaptureFormat& format));
   MOCK_METHOD1(OnStateChanged, void(VideoCaptureState state));
 
   virtual void OnDelegateAdded(int32 device_id) OVERRIDE {
@@ -79,7 +80,7 @@ TEST(VideoCaptureMessageFilterTest, Basic) {
 
   // VideoCaptureMsg_BufferReady
   int buffer_id = 22;
-  base::Time timestamp = base::Time::FromInternalValue(1);
+  base::TimeTicks timestamp = base::TimeTicks::FromInternalValue(1);
 
   media::VideoCaptureFormat format(
       gfx::Size(234, 512), 30, media::PIXEL_FORMAT_I420);