This directory contains configuration files for lint, which is run in as an upload hook for repo upload. lint.xml contains checks that are turned on or off, or whitelisted / blacklisted for particular directories, if they are different from the default. baseline.xml contains the list of existing "grandfathered" lint errors in the codebase. It is generated using ./tools/lint/update_baseline.sh When you hit a lint error that should not be triggered, there are 3 possible resolutions: 1. Use tools:ignore or @SuppressLint annotation. This is preferred for cases where the lint violation is intended, so that reviewers can review whether the suppression is appropriate. 2. Use tools/lint.xml to ignore a lint check which we don't care about for any file, or checks that are not actionable by the CL author (e.g. translation issues) 3. If there are lint errors that should be fixed, but cannot be done immediately for some reason, the issue should be added to baseline.xml. References - https://developer.android.com/studio/write/lint.html - http://tools.android.com/tips/lint-checks