Revert 170870 > Boost WaveOut thread priority for background audio. >  > XP seems to be lowering the priority of the thread responding to > audio callbacks when backgrounded, causing glitching. >  > BUG=161307 > TEST=background playback on XP works without issue. >  > Review URL: https://codereview.chromium.org/11316284
Revert 170870
> Boost WaveOut thread priority for background audio.
> 
> XP seems to be lowering the priority of the thread responding to
> audio callbacks when backgrounded, causing glitching.
> 
> BUG=161307
> TEST=background playback on XP works without issue.
> 
> Review URL: https://codereview.chromium.org/11316284

Causes hangs and high cpu usage for several users.

TBR=dalecurtis@google.com
Review URL: https://codereview.chromium.org/11638047

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@174233 0039d316-1c4b-4281-b951-d872f2087c98

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