V4L2SVDA: Add a VP9Accelerator implementation utilizing the V4L2 VP9 frame API.

media/filters/vp9_uncompressed_header_parser.cc

Index: media/filters/vp9_uncompressed_header_parser.cc
diff --git a/media/filters/vp9_uncompressed_header_parser.cc b/media/filters/vp9_uncompressed_header_parser.cc
index 2e078992057c08d23f76f157e855aa941ebf5996..43e19b98fdab3cf70acb549654ae3bb48854a69b 100644
--- a/media/filters/vp9_uncompressed_header_parser.cc
+++ b/media/filters/vp9_uncompressed_header_parser.cc
@@ -744,7 +744,7 @@ void Vp9UncompressedHeaderParser::SetupPastIndependence(Vp9FrameHeader* fhdr) {
   memset(&context_->segmentation, 0, sizeof(context_->segmentation));
   ResetLoopfilter();
   fhdr->frame_context = kVp9DefaultFrameContext;
-  DCHECK(Vp9FrameContextManager::IsValidFrameContext(fhdr->frame_context));
+  DCHECK(Vp9FrameContext::IsValid(fhdr->frame_context));
 }
 
 // 6.2.8 Loop filter params syntax
@@ -1035,21 +1035,18 @@ bool Vp9UncompressedHeaderParser::Parse(const uint8_t* stream,
     fhdr->frame_parallel_decoding_mode = reader_.ReadBool();
   }
 
-  static_assert(
-      arraysize(context_->frame_context_managers) == (1 << 2),
-      "bits of frame_context_idx doesn't match size of frame_context_managers");
   fhdr->frame_context_idx_to_save_probs = fhdr->frame_context_idx =
-      reader_.ReadLiteral(2);
+      reader_.ReadLiteral(kVp9NumFrameContextsLog2);
 
   if (fhdr->IsIntra()) {
     SetupPastIndependence(fhdr);
     if (fhdr->IsKeyframe() || fhdr->error_resilient_mode ||
         fhdr->reset_frame_context == 3) {
-      for (auto& frame_context_manage : context_->frame_context_managers)
-        frame_context_manage.Update(fhdr->frame_context);
+      for (size_t i = 0; i < kVp9NumFrameContexts; ++i)
+        context_->UpdateFrameContext(i, fhdr->frame_context);
     } else if (fhdr->reset_frame_context == 2) {
-      context_->frame_context_managers[fhdr->frame_context_idx].Update(
-          fhdr->frame_context);
+      context_->UpdateFrameContext(fhdr->frame_context_idx,
+                                   fhdr->frame_context);
     }
     fhdr->frame_context_idx = 0;
   }