Mark PreferPreviousSearch as flaky on ChromeOS.
Mark PreferPreviousSearch as flaky on ChromeOS.

BUG=32312
TBR=jshin
TEST=NONE

Review URL: http://codereview.chromium.org/550052

git-svn-id: http://src.chromium.org/svn/trunk/src@36306 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 8d2852d6a1545bbb3a796f82f93565442fbcc39e
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser