Fix a couple problems with DownloadItemGtk.
Fix a couple problems with DownloadItemGtk.

1) We were crashing after removing a download item because g_signal_handler_find() was not working as expected.
2) We had a graphical glitch with the dangerous download dialog because GtkAlignments doesn't normally redraw on allocate.

BUG=13659
Review URL: http://codereview.chromium.org/118403

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@18132 0039d316-1c4b-4281-b951-d872f2087c98

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