Android: Fix build when enable_trichrome_synchronized_proguard = true.

Broken in a recent template refactor.

Also move docs for the "verify_proguard_flags" variable to the correct
spot.

Change-Id: Ibc39995092e927b52ce02753f2105537c6ff8a11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1674441
Commit-Queue: Eric Stevenson <estevenson@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671771}
2 files changed