GitLab

Make per-bot swarming_dimensions an array.

This is in preparation for deploying the Mac ASAN bot, which will spawn
jobs on multiple GPU types.

Add "can_use_on_swarming_builders" flag for non-swarmed
tab_capture_end2end_tests.

This CL is a no-op with regard to the generated JSON files. The next CL
will add the new builder/tester.

BUG=644920
CQ_INCLUDE_TRYBOTS=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;master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=dpranke@chromium.org,maruel@chromium.org
NOTRY=true

Review-Url: https://codereview.chromium.org/2325533002
Cr-Commit-Position: refs/heads/master@{#417178}