Android: don't construct PrerenderWebMediaPlayer.
Android: don't construct PrerenderWebMediaPlayer.

PrerenderWebMediaPlayer derives from WebMediaPlayerImpl which is not
implemented on Android (there is a separate WebMediaPlayerAndroid which
is derived from the WebMediaPlayer interface). Stubbing this constructor
invocation is very difficult and it's only referred to in one place, so
an #ifdef is much simpler.

BUG=none


Review URL: https://chromiumcodereview.appspot.com/10834226

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@150774 0039d316-1c4b-4281-b951-d872f2087c98

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