Fix for crash in feedback. On sending the report, sometimes feedback seems to crash. It seems like the crash is happening in ClobberScreenshotSource, when we try to access tab_. Right before we call ClobberScreenshotSource, we CloseTabContents on the tab_ object; this probably isn't crashing in the majority case since the browser completely unloads the tab async, allowing ClobberScreenshotSource enough time to access the still valid tab_ object. There is no real reason to Clobber after the tab is closed, hence moving the call to before we actually close the tab and we're gauranteed to have a valid object in tab_
Fix for crash in feedback.
On sending the report, sometimes feedback seems to crash. It seems like the crash is happening in ClobberScreenshotSource, when we try to access tab_.
Right before we call ClobberScreenshotSource, we CloseTabContents on the tab_ object; this probably isn't crashing in the majority case since the browser completely unloads the tab async, allowing ClobberScreenshotSource enough time to access the still valid tab_ object.
There is no real reason to Clobber after the tab is closed, hence moving the call to before we actually close the tab and we're gauranteed to have a valid object in tab_

R=stevenjb@chromium.org,zelidrag@chromium.org
BUG=15253
TEST=There is no repro for this crash, so we'll have to see if this gets fixed once we push this out to users.

Review URL: http://codereview.chromium.org/7036013

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@85652 0039d316-1c4b-4281-b951-d872f2087c98

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