Splitt of CL:
https://codereview.chromium.org/2188693002/#ps100001

Switching to GN is blocked on test errors. These files are
required for compilation and allow looking into the test
errors locally.

BUG=chromium:474921
NOTRY=true

Review-Url: https://codereview.chromium.org/2190863003
Cr-Commit-Position: refs/heads/master@{#38130}