The protocol handler generator generates these files into a default location if
not specified by flag as output. We should account for these files and
explicitly set its output location.

R=machenbach@chromium.org

Committed: https://crrev.com/ac1d077db39dcabb74e36ad5d4bc7ea9fad96ed9
Review-Url: https://codereview.chromium.org/2199253002
Cr-Original-Commit-Position: refs/heads/master@{#38268}
Cr-Commit-Position: refs/heads/master@{#38273}