Update from https://crrev.com/315085

gpu/command_buffer/client/cmd_buffer_helper.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file contains the command buffer helper class.
 
 #ifndef GPU_COMMAND_BUFFER_CLIENT_CMD_BUFFER_HELPER_H_
 #define GPU_COMMAND_BUFFER_CLIENT_CMD_BUFFER_HELPER_H_
 
 #include <string.h>
@@ skipping 48 matching lines @@
   void SetAutomaticFlushes(bool enabled);
 
   // True if the context is lost.
   bool IsContextLost();
 
   // Asynchronously flushes the commands, setting the put pointer to let the
   // buffer interface know that new commands have been added. After a flush
   // returns, the command buffer service is aware of all pending commands.
   void Flush();
 
+  // Ensures that commands up to the put pointer will be processed in the
+  // command buffer service before any future commands on other command buffers
+  // sharing a channel.
+  void OrderingBarrier();
+
   // Waits until all the commands have been executed. Returns whether it
   // was successful. The function will fail if the command buffer service has
   // disconnected.
   bool Finish();
 
   // Waits until a given number of available entries are available.
   // Parameters:
   //   count: number of entries needed. This value must be at most
   //     the size of the buffer minus one.
   void WaitForAvailableEntries(int32 count);
@@ skipping 236 matching lines @@
   CommandBuffer* command_buffer_;
   int32 ring_buffer_id_;
   int32 ring_buffer_size_;
   scoped_refptr<gpu::Buffer> ring_buffer_;
   CommandBufferEntry* entries_;
   int32 total_entry_count_;  // the total number of entries
   int32 immediate_entry_count_;
   int32 token_;
   int32 put_;
   int32 last_put_sent_;
+  int32 last_barrier_put_sent_;
 
 #if defined(CMD_HELPER_PERIODIC_FLUSH_CHECK)
   int commands_issued_;
 #endif
 
   bool usable_;
   bool context_lost_;
   bool flush_automatically_;
 
   base::TimeTicks last_flush_time_;
 
   // Incremented every time the helper flushes the command buffer.
   // Can be used to track when prior commands have been flushed.
   uint32 flush_generation_;
 
   friend class CommandBufferHelperTest;
   DISALLOW_COPY_AND_ASSIGN(CommandBufferHelper);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_CMD_BUFFER_HELPER_H_