pepper: don't warn if PDF plugin is unavailable
pepper: don't warn if PDF plugin is unavailable

We preload plugins before we sandbox, then later attempt to fully
load them once we're sandboxed.  We can't ask whether the plugin
exists at the second point because we don't have disk access at
that point.  So instead, the first time we're asked about plugins
(before we're sandboxed), record whether the plugin is actually
available and use that to skip loading it in the second pass.

BUG=51546

Review URL: http://codereview.chromium.org/3114005

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@55609 0039d316-1c4b-4281-b951-d872f2087c98

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