GitLab

Make the copyrights scanner to use InputApi instead of accessing system
modules directly.

Convert manual unit tests for the scanner into automatic that now run as
a presubmit check for related changes in android_webview/tools/*

BUG=343104
NOTRY=true

Review URL: https://codereview.chromium.org/667723002

Cr-Commit-Position: refs/heads/master@{#300670}