Allow GpuPixelBrowserTest to save ref_image locally and use the local copy for future testing.
Allow GpuPixelBrowserTest to save ref_image locally and use the local copy for future testing.

So the rule is following:
1) if no ref image exist, or no ref image after a specified revision exist, or the existing ref image can't be read, save a new copy.
2) otherwise, compare with the local ref image and see if any difference in rendering.
3) if there is difference, save a FAIL_ and DIFF_ for the current rendering result.

BUG=108255
TEST=GPU waterfall
Review URL: http://codereview.chromium.org/9021003

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@115462 0039d316-1c4b-4281-b951-d872f2087c98

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