Move VideoFrame and related declarations to webrtc/api/video.

Moves webrtc/common_video/rotation.h and parts of
webrtc/common_video/include/video_frame_buffer.h and
webrtc/video_frame.h, and adds to a new GN target api:video_frame_api.

BUG=webrtc:5880

Review-Url: https://codereview.webrtc.org/2517173004
Cr-Commit-Position: refs/heads/master@{#15993}
diff --git a/webrtc/media/base/fakevideorenderer.h b/webrtc/media/base/fakevideorenderer.h
index a2e0d28..7255c05 100644
--- a/webrtc/media/base/fakevideorenderer.h
+++ b/webrtc/media/base/fakevideorenderer.h
@@ -11,9 +11,9 @@
 #ifndef WEBRTC_MEDIA_BASE_FAKEVIDEORENDERER_H_
 #define WEBRTC_MEDIA_BASE_FAKEVIDEORENDERER_H_
 
+#include "webrtc/api/video/video_frame.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/media/base/videosinkinterface.h"
-#include "webrtc/video_frame.h"
 
 namespace cricket {