Telemetry startup tests: Add more histograms to startup tests
* Track a couple more histograms in telemetry-based startup test.
* Make histograms report average value in JSON, in the case of the histograms we're interested in, only a single value is recorded so the average is the exact value and we aren't limited in resolution by the bucket width.
* Remove unneeded _Exact histogram.
BUG=None
Review URL: https://chromiumcodereview.appspot.com/14632003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@199435 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed
