Added a way for sync point clients to issue out of order waits.

components/mus/gles2/command_buffer_impl.cc

Index: components/mus/gles2/command_buffer_impl.cc
diff --git a/components/mus/gles2/command_buffer_impl.cc b/components/mus/gles2/command_buffer_impl.cc
index f7dda677d29cf97d53ef4d9ab331023f1b8db9b0..f4a581c79fafc15443221be7dc41c597a9e3aa76 100644
--- a/components/mus/gles2/command_buffer_impl.cc
+++ b/components/mus/gles2/command_buffer_impl.cc
@@ -214,7 +214,9 @@ bool CommandBufferImpl::FlushHelper(int32_t put_offset,
   // Return false if the Flush is not finished, so the CommandBufferTaskRunner
   // will not remove this task from the task queue.
   const bool complete = !driver_->HasUnprocessedCommands();
-  if (complete)
+  if (!complete)
+    driver_->sync_point_order_data()->PauseProcessingOrderNumber(order_num);
+  else
     driver_->sync_point_order_data()->FinishProcessingOrderNumber(order_num);
   return complete;
 }