Move webrtc/video_frame to common_video/include.

BUG=webrtc:7616

Review-Url: https://codereview.webrtc.org/2877703002
Cr-Commit-Position: refs/heads/master@{#18147}
diff --git a/webrtc/common_video/BUILD.gn b/webrtc/common_video/BUILD.gn
index d6005d0..043e19d 100644
--- a/webrtc/common_video/BUILD.gn
+++ b/webrtc/common_video/BUILD.gn
@@ -36,6 +36,7 @@
     "include/i420_buffer_pool.h",
     "include/incoming_video_stream.h",
     "include/video_bitrate_allocator.h",
+    "include/video_frame.h",
     "include/video_frame_buffer.h",
     "incoming_video_stream.cc",
     "libyuv/include/webrtc_libyuv.h",