Extract //gpu:gles2 into a separate component

This makes //gpu not depend on GLES2 details and will help reuse for
RasterDecoder and, later, Vulkan things.

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: I4b223e7bbd2a1596ae83feb8f7ab1f1ce2a186aa
Reviewed-on: https://chromium-review.googlesource.com/851446
Commit-Queue: Antoine Labour <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Dan Sanders <[email protected]>
Reviewed-by: Sadrul Chowdhury <[email protected]>
Reviewed-by: Victor Miura <[email protected]>
Cr-Commit-Position: refs/heads/master@{#528240}
62 files changed