All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=883791

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=6d7e53eb4804904f54baddf2f01c38b950802f37197f7b8bacbe86eb9abcd19e


Bot(s) for this bug's original alert(s):

Android Nexus6 WebView Perf

blink_perf.owp_storage - Benchmark documentation link:
  https://bit.ly/blink-perf-benchmarks

Assigning to nednguyen@google.com because this is the only CL in range:
Reshard perf benchmarks to include startup.mobile benchmark

** PERF SHERIFF: this CL may cause perf graphs to regress but it's expected **


Note that this CL also fixes a bug in sharding algorithm which makes the sharding map generation not very deterministic
(see changes to tools/perf/core/sharding_map_generator.py).

Step to generate the json files:
remove 'startup.mobile' from UNSCHEDULED_TELEMETRY_BENCHMARKS, then run:
$ ./tools/perf/generate_perf_sharding -r
$ ./tools/perf/generate_perf_data

TBR=jbudorick@chromium.org, perezju@chromium.org

Bug:  880091 ,863768
Cq-Include-Trybots: master.tryserver.chromium.perf:obbs_fyi
Change-Id: I71a2622f979d451eba53ed89f567b82d6ce549e7
Reviewed-on: https://chromium-review.googlesource.com/1214758
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#589776}

See issue 880315