Don't call FileChooser::chooseFile("") if a user selects nothing with a file chooser dialog. chooseFiles() works well even for an empty vector.
Don't call FileChooser::chooseFile("") if a user selects nothing with a file chooser dialog.
chooseFiles() works well even for an empty vector.

BUG=14162,14164
TEST=Open an image upload dialog of Gmail or Google Sites,
  Click the file upload button,
  Click the Cancel button in the file chooser dialog.
  Confirm that the dialog doesn't show "[failed]" message.

Review URL: http://codereview.chromium.org/125175

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@18696 0039d316-1c4b-4281-b951-d872f2087c98

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