GitLab

Gather a list of generated files in build_gles2_cmd_buffer.py rather
than using a manual list.

Calls format for
gpu/command_buffer/service/gles2_cmd_decoder_unittest_extensions_autogen.h,
which was previously omitted.

Review URL: https://codereview.chromium.org/573953002

Cr-Commit-Position: refs/heads/master@{#297388}