New static I420Buffer::Rotate method, to replace GetCopyWithRotationApplied.

webrtc/common_video/video_frame_buffer.cc

Index: webrtc/common_video/video_frame_buffer.cc
diff --git a/webrtc/common_video/video_frame_buffer.cc b/webrtc/common_video/video_frame_buffer.cc
index fd20e564f5e5bf855a331393d4f443975f3e8867..320758d1ecce9d9443446e3ed8fb350b431afac2 100644
--- a/webrtc/common_video/video_frame_buffer.cc
+++ b/webrtc/common_video/video_frame_buffer.cc
@@ -46,6 +46,37 @@ uint8_t* VideoFrameBuffer::MutableDataV() {
 
 VideoFrameBuffer::~VideoFrameBuffer() {}
 
+// static
+rtc::scoped_refptr<VideoFrameBuffer> VideoFrameBuffer::Rotate(
+    const rtc::scoped_refptr<VideoFrameBuffer>& src,
+    VideoRotation rotation) {

[perkj_webrtc, 2016/08/26 15:22:17]

please dcheck that src->DataY and U and V returns a pointer!=nullptr. This may
be a native handle for all we know. 

+  if (rotation == webrtc::kVideoRotation_0) {
+    return src;
+  }
+
+  int rotated_width = src->width();
+  int rotated_height = src->height();
+  if (rotation == webrtc::kVideoRotation_90 ||
+      rotation == webrtc::kVideoRotation_270) {
+    std::swap(rotated_width, rotated_height);
+  }
+
+  rtc::scoped_refptr<webrtc::I420Buffer> buffer =
+      I420Buffer::Create(rotated_width, rotated_height);
+
+  int res = libyuv::I420Rotate(
+      src->DataY(), src->StrideY(),
+      src->DataU(), src->StrideU(),
+      src->DataV(), src->StrideV(),
+      buffer->MutableDataY(), buffer->StrideY(), buffer->MutableDataU(),
+      buffer->StrideU(), buffer->MutableDataV(), buffer->StrideV(),
+      src->width(), src->height(),
+      static_cast<libyuv::RotationMode>(rotation));
+  RTC_DCHECK_EQ(res, 0);
+
+  return buffer;
+}
+
 I420Buffer::I420Buffer(int width, int height)
     : I420Buffer(width, height, width, (width + 1) / 2, (width + 1) / 2) {
 }