Parse /etc/lsb-release only once on ChromeOS
This moves all parsing and caching of the contents of /etc/lsb-release
to base::SysInfo. This eliminates redundant parsing from:
* LsbReleaseLogSource
* VersionLoader
* StatisticsProvider

BUG=266903
For chrome_main_deleagate.cc (code removal only)

R=brettw@chromium.org, derat@chromium.org, pneubeck@chromium.org, xiyuan@chromium.org
TBR=cpu@chromium.org

Review URL: https://codereview.chromium.org/23588009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225581 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225581