Add a CHECK when PluginFinder::FindPluginWithIdentifier fails.
Add a CHECK when PluginFinder::FindPluginWithIdentifier fails.

BUG=121657
TEST=none


Review URL: http://codereview.chromium.org/9969144

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@130886 0039d316-1c4b-4281-b951-d872f2087c98

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