This allows creating tests for AppRTC Android demo that will be run on
the host machine instead of a device. These tests can mock Android APIs
through Robolectric. Because the tests are run on the host machine,
they run much faster.
BUG=webrtc:5896
NOTRY=True
Review-Url: https://codereview.webrtc.org/1985663002
Cr-Commit-Position: refs/heads/master@{#12769}
