Add image contrast capability + metrics
CL contains:
1) Adding image input to atf - now it can run image contrast check and
more accurate text contrast checks
2) Fix some tests render path
3) Added separate control flags for image input (in case we need to turn
this feature off without shutting down atf integration)
4) Added additional metrics so we can monitor the perf stress due to
validator.
Bug: 150331000
Test: Able to pass all the unit tests.
Change-Id: I34f7d51fdba7551bef55b29e82291b4558b31947
(cherry picked from commit 98190e755d5422c50d6fe811e533f7de1cdc8ee8)
14 files changed
