Bug 1159753 introduced a flag histogram type which subsequently caused test failures. We don't use flag types anywhere else in the app and changing the flag to a boolean seems to fix the issue, so it's possible that flag types are broken. The failures point to build/src/ipc/chromium/src/base/histogram.cc, line 1020 Investigate and fix.
jchen, do you know what could be going wrong here? I would like us to be able to use flag histograms from Java, but this problem prevents us from doing that.
AFAIU flag histogram only expects "1" as the histogram value, to turn the flag on. To keep the value at 0, you would simply skip the add telemetry call.