Add hack that works around signaling bug that breaks Chromoting.
Add hack that works around signaling bug that breaks Chromoting.

Signaling endpoint used by chromoting doesn't always handle correctly the
case when host and client use the same stanza ID's. Workaround this issue
by adding 'x' prefix to all messages that go from client to host.

This is the same change as in crrev.com/160330 . That CL was reverted 
because it was believed that the original bug was fixed.

BUG=168617


Review URL: https://chromiumcodereview.appspot.com/11926031

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@177892 0039d316-1c4b-4281-b951-d872f2087c98

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