Use --gtest_flagfile for --gtest_filter in unit test launcher

This should help with exceeding command line length limits
with long filter strings when running a lot of tests
in the same batch.

BUG=509883

Review URL: https://codereview.chromium.org/1430633002

Cr-Commit-Position: refs/heads/master@{#356941}


CrOS-Libchrome-Original-Commit: d6c9c836e856b3d223747464f82b5586778ffc73
3 files changed
tree: bdfccfb7c532a32f3cf12150be2e976819b3a705
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/