Various //media fixes to prepare for gn check turn on.

- Remove //media/base:base_config to prevent accidental usage.
- Unify size_t and int truncation comments on a still open bug.
- Move //media/base/callback_holder.h into //media/base from unit_tests.
- Fixup //media/formats and //media/filters DEPS.
- Fixup //media/filters dependency for gpu::SyncToken

BUG=613033
TEST=cq

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: Ibc49bee9001e86e82cf39abae62f4dba93e69900
Reviewed-on: https://chromium-review.googlesource.com/622097
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#495819}
9 files changed