Implement actually decoding frames in VTVideoDecodeAccelerator.

content/common/gpu/media/vt_stubs_header.fragment

Index: content/common/gpu/media/vt_stubs_header.fragment
diff --git a/content/common/gpu/media/vt_stubs_header.fragment b/content/common/gpu/media/vt_stubs_header.fragment
index 307efaf82c7123d3dcb2fde478614511a92e9a08..f8f7ded55a609e7d4aec2d52a56220fd1b45f8b0 100644
--- a/content/common/gpu/media/vt_stubs_header.fragment
+++ b/content/common/gpu/media/vt_stubs_header.fragment
@@ -58,6 +58,12 @@ typedef OSStatus (*CMSampleBufferMakeDataReadyCallback)(
 typedef struct __CVBuffer *CVBufferRef;
 typedef CVBufferRef CVImageBufferRef;
 typedef uint32_t VTDecodeFrameFlags;
+enum {
+  kVTDecodeFrame_EnableAsynchronousDecompression = 1 << 0,
+  kVTDecodeFrame_DoNotOutputFrame = 1 << 1,
+  kVTDecodeFrame_1xRealTimePlayback = 1 << 2,
+  kVTDecodeFrame_EnableTemporalProcessing = 1 << 3,
+};
 typedef UInt32 VTDecodeInfoFlags;
 typedef struct OpaqueVTDecompressionSession* VTDecompressionSessionRef;