Fix webkit_media::WebMediaPlayerProxy memory leak due to circular refcounting.

webkit/media/webmediaplayer_proxy.cc

Index: webkit/media/webmediaplayer_proxy.cc
diff --git a/webkit/media/webmediaplayer_proxy.cc b/webkit/media/webmediaplayer_proxy.cc
index a596ed8faec274814f72830acd6ddede38a715be..cec34e3de5e9db77e2f2bd16d291c45736639147 100644
--- a/webkit/media/webmediaplayer_proxy.cc
+++ b/webkit/media/webmediaplayer_proxy.cc
@@ -50,9 +50,7 @@ void WebMediaPlayerProxy::SetVideoRenderer(
 }
 
 WebDataSourceBuildObserverHack WebMediaPlayerProxy::GetBuildObserver() {
-  if (build_observer_.is_null())
-    build_observer_ = base::Bind(&WebMediaPlayerProxy::AddDataSource, this);
-  return build_observer_;
+  return base::Bind(&WebMediaPlayerProxy::AddDataSource, this);
 }
 
 void WebMediaPlayerProxy::Paint(SkCanvas* canvas, const gfx::Rect& dest_rect) {