Android O IOT Preview 5 (OIR1.170720.015)
Merge branch 'aosp/mirror-chromium-master' into update_utils

Update toolchain_utils from ChromeOS side, which includes: initializing
Android toolchain benchmark suite and other changes since last merging.

Bug: None.
Test: None.
Change-Id: I9cd74f4377a8109872414636342be0b9f5df2db5