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

webrtc/common_video/include/video_frame_buffer.h

Index: webrtc/common_video/include/video_frame_buffer.h
diff --git a/webrtc/common_video/include/video_frame_buffer.h b/webrtc/common_video/include/video_frame_buffer.h
index 94b3d5d8330ed320c6703bcdb890dfa40b87539c..e8586ee5b5e36e1aa660f3a200841556e99cadea 100644
--- a/webrtc/common_video/include/video_frame_buffer.h
+++ b/webrtc/common_video/include/video_frame_buffer.h
@@ -18,6 +18,7 @@
 #include "webrtc/base/callback.h"
 #include "webrtc/base/refcount.h"
 #include "webrtc/base/scoped_ref_ptr.h"
+#include "webrtc/common_video/rotation.h"
 #include "webrtc/system_wrappers/include/aligned_malloc.h"
 
 namespace webrtc {
@@ -63,6 +64,10 @@ class VideoFrameBuffer : public rtc::RefCountInterface {
   // native handle.
   virtual rtc::scoped_refptr<VideoFrameBuffer> NativeToI420Buffer() = 0;
 
+  static rtc::scoped_refptr<VideoFrameBuffer> Rotate(
+      const rtc::scoped_refptr<VideoFrameBuffer>& src,
+      VideoRotation rotation);
+
  protected:
   virtual ~VideoFrameBuffer();
 };