Add support for Rec709 color space videos in software YUV convert path.

media/base/video_frame.h

Index: media/base/video_frame.h
diff --git a/media/base/video_frame.h b/media/base/video_frame.h
index ca2a2e28e0e05ffbcca8166c6994075abe167754..1527f685e8294c092588d4ed3f8ccc894c175a39 100644
--- a/media/base/video_frame.h
+++ b/media/base/video_frame.h
@@ -63,7 +63,8 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
     YV12J = 7,  // JPEG color range version of YV12
     NV12 = 8,  // 12bpp 1x1 Y plane followed by an interleaved 2x2 UV plane.
     YV24 = 9,  // 24bpp YUV planar, no subsampling.
-    FORMAT_MAX = YV24,  // Must always be equal to largest entry logged.
+    YV12HD = 10,  // Rec709 "HD" color space version of YV12
+    FORMAT_MAX = YV12HD,  // Must always be equal to largest entry logged.
   };
 
   // Returns the name of a Format as a string.