gpu: Thread-safe command buffer state lookup.

gpu/command_buffer/client/context_support.h

Index: gpu/command_buffer/client/context_support.h
diff --git a/gpu/command_buffer/client/context_support.h b/gpu/command_buffer/client/context_support.h
index c2d71734144a74fa9099779e882138c33643e452..9c38e0288d85499402eb764167d583251f16266d 100644
--- a/gpu/command_buffer/client/context_support.h
+++ b/gpu/command_buffer/client/context_support.h
@@ -25,6 +25,8 @@ class ContextSupport {
   virtual void SignalSyncToken(const SyncToken& sync_token,
                                const base::Closure& callback) = 0;
 
+  virtual bool IsFenceSyncReleased(uint64_t release_count) = 0;
+
   // Runs |callback| when a query created via glCreateQueryEXT() has cleared
   // passed the glEndQueryEXT() point.
   virtual void SignalQuery(uint32_t query, const base::Closure& callback) = 0;