Reland "Added an extra sync token field for extra command buffer..."

gpu/command_buffer/service/mailbox_manager_unittest.cc

Index: gpu/command_buffer/service/mailbox_manager_unittest.cc
diff --git a/gpu/command_buffer/service/mailbox_manager_unittest.cc b/gpu/command_buffer/service/mailbox_manager_unittest.cc
index 81979d098fa2faa6a1820716f584f3f377a0ea27..e6ce5237d23b00fc41df76e6db88639d181baf75 100644
--- a/gpu/command_buffer/service/mailbox_manager_unittest.cc
+++ b/gpu/command_buffer/service/mailbox_manager_unittest.cc
@@ -19,6 +19,7 @@ namespace gles2 {
 using namespace ::testing;
 
 static const SyncToken g_sync_token(gpu::CommandBufferNamespace::GPU_IO,
+                                    0,
                                     123,
                                     0);