Blind fix for ChromeBot crashes.
Blind fix for ChromeBot crashes.

A ChromeBot run for 172.17 was very top heavy (77/103 crashes) with:

[vector:703]	      std::vector<PasswordManagerTableModel::PasswordRow
*,std::allocator<PasswordManagerTableModel::PasswordRow *> >::size()
[browser_init.cc:140] `anonymous namespace'::NotifyNotDefaultBrowserTask::Run()
[message_loop.cc:308] MessageLoop::RunTask(Task *)

I'm going to try a null check on |tab| before we invoke
tab->infobar_delegate_count().

This applies the change made to 172 to trunk.

TBR= jcampan,ben

BUG= 11388
Review URL: http://codereview.chromium.org/99331

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@15176 0039d316-1c4b-4281-b951-d872f2087c98

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