gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/common/cmd_buffer_common.h

Index: gpu/command_buffer/common/cmd_buffer_common.h
diff --git a/gpu/command_buffer/common/cmd_buffer_common.h b/gpu/command_buffer/common/cmd_buffer_common.h
index cf09378e00c4d17630860471560d67b14a1960fb..48c92104c561af9ed09533194335b7a0bc90d54c 100644
--- a/gpu/command_buffer/common/cmd_buffer_common.h
+++ b/gpu/command_buffer/common/cmd_buffer_common.h
@@ -155,6 +155,7 @@ namespace cmd {
   OP(SetBucketDataImmediate)        /*  4 */ \
   OP(GetBucketStart)                /*  5 */ \
   OP(GetBucketData)                 /*  6 */ \
+  OP(SetAsyncToken)                 /*  7 */ \
 
 // Common commands.
 enum CommandId {
@@ -223,6 +224,29 @@ struct SetToken {
   uint32 token;
 };
 
+struct SetAsyncToken {
+  typedef SetAsyncToken ValueType;
+  static const CommandId kCmdId = kSetAsyncToken;
+  static const cmd::ArgFlags kArgFlags = cmd::kFixed;
+
+  void SetHeader() {
+    header.SetCmd<ValueType>();
+  }
+
+  void Init(uint32 _async_token) {
+    SetHeader();
+    async_token = _async_token;
+  }
+
+  static void* Set(void* cmd, uint32 async_token) {
+    static_cast<ValueType*>(cmd)->Init(async_token);
+    return NextCmdAddress<ValueType>(cmd);
+  }
+
+  CommandHeader header;
+  uint32 async_token;
+};
+
 COMPILE_ASSERT(sizeof(SetToken) == 8, Sizeof_SetToken_is_not_8);
 COMPILE_ASSERT(offsetof(SetToken, header) == 0,
                Offsetof_SetToken_header_not_0);