Exit cleanly when sending kZygoteMagic failed.
Exit cleanly when sending kZygoteMagic failed.

ChromeOS may kill chrome right after process
starts (when a user closes lid right away for example), and
sending magic number to browser process can fail. Instead of
CHECK, exit normally on chromeos.

BUG=chromium-os:17606
TEST=autotest will not crash with session manager sending SIGTERM

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=93171

Review URL: http://codereview.chromium.org/7433011

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@93222 0039d316-1c4b-4281-b951-d872f2087c98

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