gpu: Use explicit atomics instead of assuming that 32bit read/writes are atomic.

gpu/command_buffer/common/gles2_cmd_format.h

Index: gpu/command_buffer/common/gles2_cmd_format.h
diff --git a/gpu/command_buffer/common/gles2_cmd_format.h b/gpu/command_buffer/common/gles2_cmd_format.h
index a33e29e877ecd9b4aabc526f8063bb75ed4e8b2a..736c15bd73c9e4f4a3c0376b07255fb3713d41c5 100644
--- a/gpu/command_buffer/common/gles2_cmd_format.h
+++ b/gpu/command_buffer/common/gles2_cmd_format.h
@@ -12,6 +12,7 @@
 
 #include <string.h>
 
+#include "base/atomicops.h"
 #include "gpu/command_buffer/common/bitfield_helpers.h"
 #include "gpu/command_buffer/common/cmd_buffer_common.h"
 #include "gpu/command_buffer/common/gles2_cmd_ids.h"
@@ -147,7 +148,7 @@ struct QuerySync {
     result = 0;
   }
 
-  uint32 process_count;
+  base::subtle::Atomic32 process_count;
   uint64 result;
 };