Protect accessibility test against UI throttling
Protect accessibility test against UI throttling

Accessibility tests login/logout several times. This kicks in the startup job
throttling after 5 such events.

Always begin with a new UI session for each test.

BUG=None
TEST=None

R=rohitbm@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10534031

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@141065 0039d316-1c4b-4281-b951-d872f2087c98

fujunwei/chromium-crosswalk,chuan9/chromium-crosswalk,ChromiumWebApps/chromium,fujunwei/chromium-crosswalk,Just-D/chromium-1,dednal/chromium.src,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,ltilve/chromium,Pluto-tv/chromium-crosswalk,pozdnyakov/chromium-crosswalk,Pluto-tv/chromium-crosswalk,ChromiumWebApps/chromium,PeterWangIntel/chromium-crosswalk,timopulkkinen/BubbleFish,anirudhSK/chromium,bright-sparks/chromium-spacewalk,pozdnyakov/chromium-crosswalk,littlstar/chromium.src,dushu1203/chromium.src,nacl-webkit/chrome_deps,Just-D/chromium-1,chuan9/chromium-crosswalk,bright-sparks/chromium-spacewalk,ChromiumWebApps/chromium,jaruba/chromium.src,mogoweb/chromium-crosswalk,Just-D/chromium-1,bright-sparks/chromium-spacewalk,ChromiumWebApps/chromium,keishi/chromium,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,hgl888/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,junmin-zhu/chromium-rivertrail,axinging/chromium-crosswalk,hgl888/chromium-crosswalk,Fireblend/chromium-crosswalk,M4sse/chromium.src,hgl888/chromium-crosswalk,hujiajie/pa-chromium,hgl888/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,keishi/chromium,axinging/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,dednal/chromium.src,ChromiumWebApps/chromium,hgl888/chromium-crosswalk-efl,dushu1203/chromium.src,keishi/chromium,ltilve/chromium,junmin-zhu/chromium-rivertrail,Chilledheart/chromium,keishi/chromium,jaruba/chromium.src,M4sse/chromium.src,mohamed--abdel-maksoud/chromium.src,Jonekee/chromium.src,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,littlstar/chromium.src,littlstar/chromium.src,axinging/chromium-crosswalk,ondra-novak/chromium.src,Just-D/chromium-1,mohamed--abdel-maksoud/chromium.src,timopulkkinen/BubbleFish,Jonekee/chromium.src,fujunwei/chromium-crosswalk,jaruba/chromium.src,Chilledheart/chromium,crosswalk-project/chromium-crosswalk-efl,zcbenz/cefode-chromium,krieger-od/nwjs_chromium.src,Jonekee/chromium.src,Just-D/chromium-1,littlstar/chromium.src,ltilve/chromium,dednal/chromium.src,nacl-webkit/chrome_deps,TheTypoMaster/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,nacl-webkit/chrome_deps,krieger-od/nwjs_chromium.src,krieger-od/nwjs_chromium.src,TheTypoMaster/chromium-crosswalk,ltilve/chromium,chuan9/chromium-crosswalk,Fireblend/chromium-crosswalk,zcbenz/cefode-chromium,dednal/chromium.src,nacl-webkit/chrome_deps,hujiajie/pa-chromium,ChromiumWebApps/chromium,ltilve/chromium,dednal/chromium.src,hgl888/chromium-crosswalk,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,zcbenz/cefode-chromium,zcbenz/cefode-chromium,axinging/chromium-crosswalk,junmin-zhu/chromium-rivertrail,krieger-od/nwjs_chromium.src,markYoungH/chromium.src,ChromiumWebApps/chromium,M4sse/chromium.src,Pluto-tv/chromium-crosswalk,bright-sparks/chromium-spacewalk,keishi/chromium,Jonekee/chromium.src,Fireblend/chromium-crosswalk,markYoungH/chromium.src,Chilledheart/chromium,patrickm/chromium.src,hujiajie/pa-chromium,timopulkkinen/BubbleFish,ondra-novak/chromium.src,hgl888/chromium-crosswalk,anirudhSK/chromium,M4sse/chromium.src,anirudhSK/chromium,pozdnyakov/chromium-crosswalk,patrickm/chromium.src,nacl-webkit/chrome_deps,ltilve/chromium,pozdnyakov/chromium-crosswalk,junmin-zhu/chromium-rivertrail,keishi/chromium,mohamed--abdel-maksoud/chromium.src,ChromiumWebApps/chromium,timopulkkinen/BubbleFish,crosswalk-project/chromium-crosswalk-efl,littlstar/chromium.src,junmin-zhu/chromium-rivertrail,dushu1203/chromium.src,bright-sparks/chromium-spacewalk,Jonekee/chromium.src,chuan9/chromium-crosswalk,timopulkkinen/BubbleFish,timopulkkinen/BubbleFish,markYoungH/chromium.src,nacl-webkit/chrome_deps,TheTypoMaster/chromium-crosswalk,Just-D/chromium-1,anirudhSK/chromium,bright-sparks/chromium-spacewalk,pozdnyakov/chromium-crosswalk,M4sse/chromium.src,nacl-webkit/chrome_deps,ondra-novak/chromium.src,jaruba/chromium.src,hujiajie/pa-chromium,hgl888/chromium-crosswalk-efl,fujunwei/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,chuan9/chromium-crosswalk,mogoweb/chromium-crosswalk,Pluto-tv/chromium-crosswalk,krieger-od/nwjs_chromium.src,Jonekee/chromium.src,anirudhSK/chromium,Pluto-tv/chromium-crosswalk,ltilve/chromium,hujiajie/pa-chromium,Just-D/chromium-1,keishi/chromium,dednal/chromium.src,chuan9/chromium-crosswalk,M4sse/chromium.src,mogoweb/chromium-crosswalk,jaruba/chromium.src,crosswalk-project/chromium-crosswalk-efl,Chilledheart/chromium,M4sse/chromium.src,M4sse/chromium.src,axinging/chromium-crosswalk,nacl-webkit/chrome_deps,TheTypoMaster/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,jaruba/chromium.src,zcbenz/cefode-chromium,anirudhSK/chromium,jaruba/chromium.src,timopulkkinen/BubbleFish,ChromiumWebApps/chromium,jaruba/chromium.src,zcbenz/cefode-chromium,keishi/chromium,Chilledheart/chromium,littlstar/chromium.src,dednal/chromium.src,Chilledheart/chromium,axinging/chromium-crosswalk,axinging/chromium-crosswalk,nacl-webkit/chrome_deps,fujunwei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