Add prototype D3D11VideoDecodeAccelerator.

media/gpu/h264_dpb.cc

Index: media/gpu/h264_dpb.cc
diff --git a/media/gpu/h264_dpb.cc b/media/gpu/h264_dpb.cc
index 150bd31f6f110f30b177561bb1ac6173816bf7b7..3cc32a6247a30f9e1902f76100ffd8880e3e5087 100644
--- a/media/gpu/h264_dpb.cc
+++ b/media/gpu/h264_dpb.cc
@@ -62,7 +62,7 @@ void H264DPB::Clear() {
 }
 
 void H264DPB::set_max_num_pics(size_t max_num_pics) {
-  DCHECK_LE(max_num_pics, kDPBMaxSize);
+  DCHECK_LE(max_num_pics, static_cast<size_t>(kDPBMaxSize));
   max_num_pics_ = max_num_pics;
   if (pics_.size() > max_num_pics_)
     pics_.resize(max_num_pics_);