tools/gn: another round of fixes to keep bootstrap working

This patch includes metrics_hashes.cc and md5.cc to the base's sources
list to fix the undefined errors as below:

base/metrics/histogram.o: In function
`base::Histogram::Histogram(std::string const&, int, int, base::BucketRanges const*)':
histogram.cc:(.text+0xfc0): undefined reference to `base::HashMetricName(std::string const&)'

BUG=569821
TEST=./tools/gn/bootstrap/bootstrap.py
TBR=brettw@chromium.org

Review URL: https://codereview.chromium.org/1534313002

Cr-Original-Commit-Position: refs/heads/master@{#366194}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 9608e1467c41eaabab78e68da96a00f475aa25d6
1 file changed
tree: 209e318ac5f0f6990377b43caeda419c604795ec
  1. tools/