Don't require VDAs to return all PictureBuffers at once.

media/video/video_decode_accelerator.h

Index: media/video/video_decode_accelerator.h
diff --git a/media/video/video_decode_accelerator.h b/media/video/video_decode_accelerator.h
index e2bcdf64855fdf3455fc0a3b73ae2b59c2e928e6..863aafc9155af66e3255fceb74388e4c9d7001ed 100644
--- a/media/video/video_decode_accelerator.h
+++ b/media/video/video_decode_accelerator.h
@@ -34,6 +34,21 @@ class MEDIA_EXPORT VideoDecodeAccelerator {
   };
   using SupportedProfiles = std::vector<SupportedProfile>;
 
+  struct MEDIA_EXPORT Capabilities {
+    Capabilities();
+    // Flags that can be associated with a VDA.
+    enum Flags {
+      kNoFlags = 0,
+
+      // If set, then the VDA makes no guarantees that it won't stall before
+      // sending all the picture buffers to the client via PictureReady.
+      kCanStallAnytime = 1 << 0,
+    };
+
+    SupportedProfiles supported_profiles;
+    Flags flags;
+  };
+
   // Enumeration of potential errors generated by the API.
   // Note: Keep these in sync with PP_VideoDecodeError_Dev. Also do not
   // rearrange, reuse or remove values as they are used for gathering UMA