[Cronet] Hook up library loader, system proxy and network change notifier to async api.

components/cronet/android/cronet_url_request_adapter.cc

Index: components/cronet/android/cronet_url_request_adapter.cc
diff --git a/components/cronet/android/cronet_url_request_adapter.cc b/components/cronet/android/cronet_url_request_adapter.cc
index e16ebe1c49dc0a8f701c98514a4b0f7ab1da29b4..49922d2011b1836cc4e3684f9f7f4aa15cac2ec2 100644
--- a/components/cronet/android/cronet_url_request_adapter.cc
+++ b/components/cronet/android/cronet_url_request_adapter.cc
@@ -47,15 +47,15 @@ void CronetURLRequestAdapter::DisableCache() {
   load_flags_ |= net::LOAD_DISABLE_CACHE;
 }
 
-bool CronetURLRequestAdapter::PostTaskToNetworkThread(
+void CronetURLRequestAdapter::PostTaskToNetworkThread(
     const tracked_objects::Location& from_here,
     const base::Closure& task) {
   DCHECK(!IsOnNetworkThread());
-  return context_->GetNetworkTaskRunner()->PostTask(from_here, task);
+  context_->PostTaskToNetworkThread(from_here, task);
 }
 
 bool CronetURLRequestAdapter::IsOnNetworkThread() const {
-  return context_->GetNetworkTaskRunner()->BelongsToCurrentThread();
+  return context_->IsOnNetworkThread();
 }
 
 void CronetURLRequestAdapter::Start() {