Fix crash on it2me disconnect on the mac.
Fix crash on it2me disconnect on the mac.

In it2me, the destructor of EventExecutor does not get called in the same thread
from where it's used. This is causing the Timer object used in EventExecutorMac
to CHECK in the destructor because it requires that it be destroyed in the same
thread where it was first started - even if it has already been stopped.

So instead of reusing the Timer and starting and stopping it on demand,
EventExecutorMac will now create and destroy the timer on session start and
stop, respectively.

BUG=133017
TEST=Connect and disconnect with it2me. Repeat with me2me.


Review URL: https://chromiumcodereview.appspot.com/10557012

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@143089 0039d316-1c4b-4281-b951-d872f2087c98

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