Add PIXEL_FORMAT_MT21.

media/base/video_types.cc

Index: media/base/video_types.cc
diff --git a/media/base/video_types.cc b/media/base/video_types.cc
index 627fc8e7cd9d2e603006a48c20db4bc8094c3fe3..b6b041ee4718e48d9e89067b7ccd595a44115b80 100644
--- a/media/base/video_types.cc
+++ b/media/base/video_types.cc
@@ -40,6 +40,8 @@ std::string VideoPixelFormatToString(VideoPixelFormat format) {
       return "PIXEL_FORMAT_RGB32";
     case PIXEL_FORMAT_MJPEG:
       return "PIXEL_FORMAT_MJPEG";
+    case PIXEL_FORMAT_MT21:
+      return "PIXEL_FORMAT_MT21";
   }
   NOTREACHED() << "Invalid VideoPixelFormat provided: " << format;
   return "";
@@ -54,6 +56,7 @@ bool IsYuvPlanar(VideoPixelFormat format) {
     case PIXEL_FORMAT_YV24:
     case PIXEL_FORMAT_NV12:
     case PIXEL_FORMAT_NV21:
+    case PIXEL_FORMAT_MT21:
       return true;
 
     case PIXEL_FORMAT_UNKNOWN: