Mac Video Capture: Sending the timestamps provided by the driver to the capture pipeline

media/capture/video/mac/video_capture_device_qtkit_mac.mm

Index: media/capture/video/mac/video_capture_device_qtkit_mac.mm
diff --git a/media/capture/video/mac/video_capture_device_qtkit_mac.mm b/media/capture/video/mac/video_capture_device_qtkit_mac.mm
index 1ea4c9e44988f8cfb18d5f03ba8f2c13f236d948..de77a346987ea3d2d0033f9b5a67ea8b859532c9 100644
--- a/media/capture/video/mac/video_capture_device_qtkit_mac.mm
+++ b/media/capture/video/mac/video_capture_device_qtkit_mac.mm
@@ -325,8 +325,19 @@
     }
 
     // Deliver the captured video frame.
+    const QTTime qt_timestamp = [sampleBuffer presentationTime];
+    base::TimeTicks timestamp;
+    if (!(qt_timestamp.flags & kQTTimeIsIndefinite) && qt_timestamp.timeScale) {
+      timestamp =
+          base::TimeTicks() +
+          base::TimeDelta::FromMicroseconds(
+              qt_timestamp.timeValue * base::TimeTicks::kMicrosecondsPerSecond /
+              qt_timestamp.timeScale);
+    } else {
+      timestamp = base::TimeTicks::Now();
+    }
     frameReceiver_->ReceiveFrame(addressToPass, frameSize, captureFormat,
-                                 aspectNumerator, aspectDenominator);
+                                 aspectNumerator, aspectDenominator, timestamp);
 
     CVPixelBufferUnlockBaseAddress(videoFrame, kLockFlags);
   }