VideoToolbox encoder for cast senders.

media/cast/sender/video_sender.cc

Index: media/cast/sender/video_sender.cc
diff --git a/media/cast/sender/video_sender.cc b/media/cast/sender/video_sender.cc
index 190e9648d52ad4a6ffd85772b4046c903c76f160..a34b55f8cf46edfa23766746ddbd6563069ff393 100644
--- a/media/cast/sender/video_sender.cc
+++ b/media/cast/sender/video_sender.cc
@@ -17,6 +17,10 @@
 #include "media/cast/sender/video_encoder_impl.h"
 #include "media/cast/sender/video_frame_factory.h"
 
+#if defined(OS_MACOSX)
+#include "media/cast/sender/h264_vt_encoder.h"
+#endif
+
 namespace media {
 namespace cast {
 
@@ -70,6 +74,18 @@ VideoSender::VideoSender(
       weak_factory_(this) {
   cast_initialization_status_ = STATUS_VIDEO_UNINITIALIZED;
 
+#if defined(OS_MACOSX)
+  // On Apple platforms, use the hardware H.264 encoder if possible. It is the
+  // only reasonable option for iOS.
+  if (!video_config.use_external_encoder &&
+      video_config.codec == CODEC_VIDEO_H264) {
+    video_encoder_.reset(new H264VideoToolboxEncoder(
+        cast_environment, video_config,
+        base::Bind(&VideoSender::OnEncoderInitialized,
+                   weak_factory_.GetWeakPtr(), initialization_cb)));
+  }
+#endif  // defined(OS_MACOSX)
+#if !defined(OS_IOS)
   if (video_config.use_external_encoder) {
     video_encoder_.reset(new ExternalVideoEncoder(
         cast_environment,
@@ -78,11 +94,12 @@ VideoSender::VideoSender(
                    weak_factory_.GetWeakPtr(), initialization_cb),
         create_vea_cb,
         create_video_encode_mem_cb));
-  } else {
+  } else if (!video_encoder_) {
     // Software encoder is initialized immediately.
     video_encoder_.reset(new VideoEncoderImpl(cast_environment, video_config));
     cast_initialization_status_ = STATUS_VIDEO_INITIALIZED;
   }
+#endif  // !defined(OS_IOS)
 
   if (cast_initialization_status_ == STATUS_VIDEO_INITIALIZED) {
     cast_environment->PostTask(