Prevent being caught in a drag without the correct set up being first performed, caused by some strange context menu interactions. This doesn't fix why we're in this situation, only a band-aid for any problems it could cause. BUG=25682 TEST=clicking tabs, dragging tabs, closing tabs, anything with tabs, and the case covered in the bug to ensure there are no crashes. Review URL: http://codereview.chromium.org/355027
Prevent being caught in a drag without the correct set up being first performed, caused by some strange context menu interactions. This doesn't fix why we're in this situation, only a band-aid for any problems it could cause.
BUG=25682
TEST=clicking tabs, dragging tabs, closing tabs, anything with tabs, and the case covered in the bug to ensure there are no crashes.
Review URL: http://codereview.chromium.org/355027

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@31237 0039d316-1c4b-4281-b951-d872f2087c98

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