Revert 61124 To see if interactive_ui_test (AutocompleteEditViewTest) go green.
Revert 61124 To see if interactive_ui_test (AutocompleteEditViewTest)
go green.

Disk Cache: Add a quick return path for truncating an empty stream
and make sure that Flush() doesn't fail when it has nothing to do.

BUG=56872, 57395
TEST=none

Review URL: http://codereview.chromium.org/3551005

TBR=rvargas@google.com

Review URL: http://codereview.chromium.org/3543007

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@61138 0039d316-1c4b-4281-b951-d872f2087c98

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