Replace VideoDecoder::media_format() with significantly simpler width()/height() methods.

media/base/video_decoder_config.h

Index: media/base/video_decoder_config.h
diff --git a/media/base/video_decoder_config.h b/media/base/video_decoder_config.h
index 011efbfedae6fd9a3b86dc495ab511e543d6a97e..a077312e7ed0a63d1b70553b58b6f604aff0e273 100644
--- a/media/base/video_decoder_config.h
+++ b/media/base/video_decoder_config.h
@@ -18,6 +18,11 @@ enum VideoCodec {
   kCodecMPEG4,
   kCodecTheora,
   kCodecVP8,
+
+  // DO NOT ADD RANDOM VIDEO CODECS!
+  //
+  // The only acceptable time to add a new codec is if there is production code
+  // that uses said codec in the same CL.
 };
 
 class VideoDecoderConfig {