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

gpu/command_buffer/common/gles2_cmd_format.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines the GLES2 command buffer commands.
 
 #ifndef GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_H_
 #define GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_H_
 
 
@@ skipping 129 matching lines @@
   // ProgramInput inputs[num_attribs + num_uniforms];
 };
 
 // The format of QuerySync used by EXT_occlusion_query_boolean
 struct QuerySync {
   void Reset() {
     process_count = 0;
     result = 0;
   }
 
-  uint32 process_count;
+  int32 process_count;

[Dmitry Vyukov, 2014/03/04 08:07:56]

s/int32/Atomic32/

[reveman, 2014/03/06 21:05:42]

Done.

   uint64 result;
 };
 
 COMPILE_ASSERT(sizeof(ProgramInput) == 20, ProgramInput_size_not_20);
 COMPILE_ASSERT(offsetof(ProgramInput, type) == 0,
                OffsetOf_ProgramInput_type_not_0);
 COMPILE_ASSERT(offsetof(ProgramInput, size) == 4,
                OffsetOf_ProgramInput_size_not_4);
 COMPILE_ASSERT(offsetof(ProgramInput, location_offset) == 8,
                OffsetOf_ProgramInput_location_offset_not_8);
@@ skipping 278 matching lines @@
   CommandHeader header;
 };
 
 #pragma pack(pop)
 
 }  // namespace cmd
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_H_