Break a single histogram into two histograms
This histogram records a networking result that if positive indicates a
byte count, and if negative indicates an error code. Since histograms
can't handle negative values, this splits that up into two: one for the
byte count, and one that will use an existing enum for the network
error code.
This was based off of a suggestion in codereview.chromium.org/
236023005
BUG=360909
Review URL: https://codereview.chromium.org/
235893017
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@264323 0039d316-1c4b-4281-b951-d872f2087c98