Use base::AtomicSequenceNumber for the flush id in GLES2Implementation

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 9bb62324ec89a1e116803cb62f01832f9b04cf1d..38a3acd868d51ee01a3085c67503ef70b993af65 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -17,6 +17,7 @@
 #include <set>
 #include <sstream>
 #include <string>
+#include "base/atomic_sequence_num.h"
 #include "base/compiler_specific.h"
 #include "base/strings/string_split.h"
 #include "base/strings/stringprintf.h"
@@ -77,10 +78,8 @@ GLuint ToGLuint(const void* ptr) {
 }
 
 uint32_t GenerateNextFlushId() {
-  static base::subtle::Atomic32 flush_id = 0;
-  base::subtle::Atomic32 my_id =
-      base::subtle::Barrier_AtomicIncrement(&flush_id, 1);
-  return static_cast<uint32_t>(my_id);
+  static base::AtomicSequenceNumber flush_id;

[piman, 2016/03/16 23:49:29]

I was thinking, move this out of the function and as a
StaticAtomicSequenceNumber, to avoid the constructor/destructor

[danakj, 2016/03/16 23:50:41]

Oh, snap. Sure :)

+  return static_cast<uint32_t>(flush_id.GetNext());
 }
 
 }  // anonymous namespace