Mute ALSA audio completely
Mute ALSA audio completely

The PCM control is needed to mute audio completely, but it is not available until at least one pcm stream is opened.  This fix just opens and closes a pcm stream before gathering information about which mixer controls are available.

BUG=chromium-os:12151
TEST=Manual, play audio then mute.  No audio should be heard through headphones.

Review URL: http://codereview.chromium.org/6591095

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@76943 0039d316-1c4b-4281-b951-d872f2087c98

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