crosperf: refactor chrome src search

Replace multiple levels of if/else of the chrome src search with a loop.
Add a missing search path .cache/distfiles/chrome-src.
Add checks for the Chrome source location and raise RuntimeError if it
does not exist.

BUG=None
TEST=Tested with crosperf and distfiles/target/chrome-src-internal.

Change-Id: I66dd7c802a4e80238e4d625586198bdf573621dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2453595
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Caroline Tice <cmtice@chromium.org>
Tested-by: Denis Nikitin <denik@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
1 file changed