Mac Video Capture: Connect error logging to WebRTC Log

media/video/capture/mac/video_capture_device_mac.mm

Index: media/video/capture/mac/video_capture_device_mac.mm
diff --git a/media/video/capture/mac/video_capture_device_mac.mm b/media/video/capture/mac/video_capture_device_mac.mm
index fb477190f9a73cf9516d8e92e166d7135585ef4e..12cd9f85a3673a574f7c9ddfe9ee9d9a1010007e 100644
--- a/media/video/capture/mac/video_capture_device_mac.mm
+++ b/media/video/capture/mac/video_capture_device_mac.mm
@@ -378,6 +378,10 @@ void VideoCaptureDeviceMac::AllocateAndStart(
     GetBestMatchSupportedResolution(&width, &height);
 
   client_ = client.Pass();
+  if (device_name_.capture_api_type() == Name::AVFOUNDATION)
+    Log("Using AVFoundation for device: " + device_name_.name());
+  else
+    Log("Using QTKit for device: " + device_name_.name());
   NSString* deviceId =
       [NSString stringWithUTF8String:device_name_.id().c_str()];
 
@@ -560,6 +564,12 @@ void VideoCaptureDeviceMac::SetErrorState(const std::string& reason) {
   client_->OnError(reason);
 }
 
+void VideoCaptureDeviceMac::Log(const std::string& message) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (client_)
+    client_->OnLog(message);
+}
+
 bool VideoCaptureDeviceMac::UpdateCaptureResolution() {
  if (![capture_device_ setCaptureHeight:capture_format_.frame_size.height()
                                   width:capture_format_.frame_size.width()