[Bundles] Add Bundle support to Trichrome Chrome

This CL adds the trichrome_chrome_bundle target. A caveat is that in
order to make Trichrome Chrome use the same ARM bitness as Trichrome
Library, we need to inject "native_lib_placeholders" files (e.g.,
"libdummy.so") to the Trichrome base module. Implementation:
* For monochrome_public_bundle_tmpl -> android_app_bundle: Pass
  |add_native_lib_placeholders_for_base_module| flag for Trichrome.
* The above flag causes android_app_bundle to pass placeholder
  params to create_android_app_bundle_module, which then adds the
  proper flags to apkbuilder.py call.

Change-Id: I8d7355bd052166b51aa9b8336f9436d975661a28
Reviewed-on: https://chromium-review.googlesource.com/c/1487837
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Christopher Grant <cjgrant@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637295}
3 files changed