gpu: split gles2-specific files into separate source_sets

They all still go into a single component, but that is starting to
clarify dependencies. This (mostly) doesn't include code changes,
beyond removing useless/harmful headers.

Some pieces are not into their final target, because they require code
changes/refactoring, which will go into future CLs.

Bug: 795884
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I69effc2af24d0363392a68b4ef3b2c3ab097c876
Reviewed-on: https://chromium-review.googlesource.com/833178
Reviewed-by: Dan Sanders <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Victor Miura <[email protected]>
Commit-Queue: Antoine Labour <[email protected]>
Cr-Commit-Position: refs/heads/master@{#525064}
15 files changed