The implementation creates an Android hardware video decoder. It is built around the same patterns as the HardwareVideoEncoderFactory. This change pulls some shared code and constants into a common "utils" class. Finally, adds an instrumentation test for the HardwareVideoDecoder. BUG=webrtc:7760 Change-Id: Iea6eaae7727925743cb54f7c3153a6c07d62f55d Reviewed-on: https://chromium-review.googlesource.com/536254 Commit-Queue: Bjorn Mellem <mellem@webrtc.org> Reviewed-by: Sami Kalliomäki <sakal@webrtc.org> Reviewed-by: Peter Thatcher <pthatcher@webrtc.org> Cr-Commit-Position: refs/heads/master@{#18686}