Add OrderingBarrierCHROMIUM API.

gpu/command_buffer/client/cmd_buffer_helper.cc

Index: gpu/command_buffer/client/cmd_buffer_helper.cc
diff --git a/gpu/command_buffer/client/cmd_buffer_helper.cc b/gpu/command_buffer/client/cmd_buffer_helper.cc
index a99201e4b36164ef01ef218d7651f6fe55e851b9..038ba41fda06ae7b10e2d73b91e9423d2b1d8410 100644
--- a/gpu/command_buffer/client/cmd_buffer_helper.cc
+++ b/gpu/command_buffer/client/cmd_buffer_helper.cc
@@ -150,7 +150,7 @@ void CommandBufferHelper::Flush() {
   if (put_ == total_entry_count_)
     put_ = 0;
 
-  if (usable() && last_put_sent_ != put_) {
+  if (usable()) {
     last_flush_time_ = base::TimeTicks::Now();
     last_put_sent_ = put_;
     command_buffer_->Flush(put_);
@@ -159,6 +159,18 @@ void CommandBufferHelper::Flush() {
   }
 }
 
+void CommandBufferHelper::OrderingBarrier() {
+  // Wrap put_ before setting the barrier.
+  if (put_ == total_entry_count_)
+    put_ = 0;
+
+  if (usable()) {
+    command_buffer_->OrderingBarrier(put_);
+    ++flush_generation_;
+    CalcImmediateEntries(0);
+  }
+}
+
 #if defined(CMD_HELPER_PERIODIC_FLUSH_CHECK)
 void CommandBufferHelper::PeriodicFlushCheck() {
   base::TimeTicks current_time = base::TimeTicks::Now();