Try to fix Crash at gfx::CGImageToSkBitmap.
Try to fix Crash at gfx::CGImageToSkBitmap.

The fix is to add the check for NULL context since skia::BitmapPlatformDevice::Create might return NULL.

BUG=54880
TEST=none

Review URL: http://codereview.chromium.org/3352014

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@58952 0039d316-1c4b-4281-b951-d872f2087c98

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