Android: Fix generate_gradle.py handling tests

- Correctly handle generated files in test entries.
- Fix fast to still output prebuilt jars.
  - Moving towards making `--fast` only generate what is necessary.
  - Still room to improve in avoiding tons of copies of the same mojom
    generated java files in many gn targets.

Bug: 620034
Change-Id: I651cd0684c4388b90181638023e25a027c2d8949
Reviewed-on: https://chromium-review.googlesource.com/1169694
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582690}
1 file changed