PinnedLauncherAppsPolicyHandler accepts Chrome extension IDs as well
as Android app IDs, but it was derived from ExtensionListPolicyHandler,
which actually filters out Android app IDs.

It works more or less by accident only since PinnedLauncherAppsPolicyHandler bypasses the filtering by overriding ApplyPolicySettings. Moreover, errors are added to chrome://policy whenever an Android app is pinned.