[DO NOT MERGE] Allow compilation with Jack.

Adapt to Jack compilation specifics.

Fix bad import in VideoDumpActivity.
The extra semicolumn is ignored by javac because of
https://bugs.openjdk.java.net/browse/JDK-8027682 but is not
permitted by ecj or Jack.

This includes cherry-picks of the following changes:
248ef6f9
705555dc
f50a51fb
bf5ad8d9

Change-Id: Ifbe063e3822a7d63b1681921b9788cfca898ba64