Fix z-order problem and cleanup a few nits.
Fix z-order problem and cleanup a few nits.

Original patch: https://codereview.chromium.org/59043012/

The issue this patch addresses is that if a user has 
multiple chrome windows open (e.g. press Ctrl+N a few 
times), and then change the chrome theme or windows desktop 
theme, after the theme is changed the windows will be 
non-deterministically re-arranged in the z-order.

BUG=312535, 311405

Review URL: https://codereview.chromium.org/60743003

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@234968 0039d316-1c4b-4281-b951-d872f2087c98

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