Add support for autofill server experiments

BUG=none
TEST=unit_tests --gtest_filter=AutoFillMetricsTest.QualityMetricsWithExperimentId:AutoFillQueryXmlParserTest.ParseExperimentId

Review URL: http://codereview.chromium.org/6260027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@73216 0039d316-1c4b-4281-b951-d872f2087c98
AutoFillMetrics::~AutoFillMetrics() {
}

AutoFillMetrics::~AutoFillMetrics() {
}
