Icon densities validation

Icon densities validation

Icons will look best if a custom version is provided for each of the major screen density classes (low, medium, high, extra high). This lint check identifies icons which do not have complete coverage across the densities.

Low density is not really used much anymore, so this check ignores the ldpi density. To force lint to include it, set the environment variable ANDROID_LINT_INCLUDE_LDPI=true. For more information on current density usage, see https://developer.android.com/about/dashboards

Issue id: IconDensities

https://developer.android.com/guide/practices/screens_support.html