gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/client/cmd_buffer_helper.h

Index: gpu/command_buffer/client/cmd_buffer_helper.h
diff --git a/gpu/command_buffer/client/cmd_buffer_helper.h b/gpu/command_buffer/client/cmd_buffer_helper.h
index 49230b47fb501af288bed75fe2068a22705f7878..a2de5ac8bf7089410d3bfaa992415ff06e1a26aa 100644
--- a/gpu/command_buffer/client/cmd_buffer_helper.h
+++ b/gpu/command_buffer/client/cmd_buffer_helper.h
@@ -84,6 +84,15 @@ class GPU_EXPORT CommandBufferHelper {
   //   shutdown.
   int32 InsertToken();
 
+  // Returns true if the token has passed.
+  // Parameters:
+  //   the value of the token to check whether it has passed
+  bool HasTokenPassed(int32 token) const {
+    if (token > token_)
+      return true;  // we wrapped
+    return last_token_read() >= token;
+  }
+
   // Waits until the token of a particular value has passed through the command
   // stream (i.e. commands inserted before that token have been executed).
   // NOTE: This will call Flush if it needs to block.