Initial commit of our new Android app to demo Skia.

Initial commit of our new Android app to demo Skia.

Currently, there's only a simple Activity with a title bar and a surface view
that connects with Skia viewer native application.

Before integrating user action events, I want to make sure that the design and
implementation so far are good.  Note that the old NativeApplication-based
Activity (ViewerActivity) is still there for reference and test purposes. It
will be removed eventually.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1952323004

Review-Url: https://codereview.chromium.org/1952323004