Re-land: gpu: Add CHROMIUM_sync_query extension.

gpu/command_buffer/build_gles2_cmd_buffer.py

Index: gpu/command_buffer/build_gles2_cmd_buffer.py
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 84d70c0d4111c51ea22ad0228d8a04bb01f9d929..7105edf4cbba65287f84f4e57e366b2cc43b3ab5 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -841,6 +841,7 @@ _ENUM_LISTS = {
       'GL_LATENCY_QUERY_CHROMIUM',
       'GL_ASYNC_PIXEL_UNPACK_COMPLETED_CHROMIUM',
       'GL_ASYNC_PIXEL_PACK_COMPLETED_CHROMIUM',
+      'GL_COMMANDS_COMPLETED_CHROMIUM',

[piman, 2014/04/16 00:32:03]

We should only add this to the set of valid enums if the necessary underlying
extensions are available (i.e. in feature_info.cc)

[reveman, 2014/04/16 01:28:47]

I'm assuming it's OK to handle this in HandleBeginQueryEXT where
ANY_SAMPLES_PASSED_* enums are validated.

     ],
   },
   'RenderBufferParameter': {