Infobar -> InfoBar, for consistency with the rest of the codebase

BUG=none
TEST=none

Review URL: https://codereview.chromium.org/83483013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236928 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236928
Remove plugin_list param from MetricsLog::RecordStabilityMetrics.

Instead, use the list of plugins that have already been
set on the system profile. This makes the API simpler and
paves way for my upcoming change to log initial stability
metrics in their own log. The new code is also slightly
more efficient, since there's fewer string conversions.

Also adds tests coverage for the functionality, which was
previously untested.

BUG=312733
TEST=New unit test.

Review URL: https://codereview.chromium.org/83023006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236929 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236929