This is a follow up CL to my previous CL [1], which enabled us to test
Direct-Reply with EditTextVariations.
What this CL does are:
* Specyfing min_sdk_version to avoid INSTALL_FAILED_OLDER_SDK error
when installing on older devices.
* Avoiding NoSuchMethodError on pre-O devices where
Notification.Builder does not have a constructor that takes
notification channel.
* Fixing a race condition where notification can be sent before
notification channel is created.
[1]: Iafffcc7d138b0f502116a5e557f0c3f17e9d0b73
da2486fd63
Bug: 122957841
Test: Made sure that we can install EditTextVariations on N devices
and "Direct-Reply" on EditTextVariations works there.
Change-Id: Ib4fbd447608b111e763fde4287226cf7e206e65e
