Revert "cbuildbot: tie the cache for chrome src per branch"

This reverts commit 3e27271a68c4248267acc05f330bb78a90936838.

BUG=chromium:658504
TEST=None

Change-Id: I8eb4bc6c445dfd5e7bea0f8184ef1094edc11904
Reviewed-on: https://chromium-review.googlesource.com/401284
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
1 file changed