Reland r288013: First cut at "content handling" support in Mojo.

mojo/shell/network_service_loader.cc

Index: mojo/shell/network_service_loader.cc
diff --git a/mojo/shell/network_service_loader.cc b/mojo/shell/network_service_loader.cc
index 9f8f87f0b7f62ada1c6a8f836e061f58797005f7..8e5cff2d7bcb4f076a452b2dbb26721c436963a3 100644
--- a/mojo/shell/network_service_loader.cc
+++ b/mojo/shell/network_service_loader.cc
@@ -29,10 +29,13 @@ NetworkServiceLoader::NetworkServiceLoader() {
 NetworkServiceLoader::~NetworkServiceLoader() {
 }
 
-void NetworkServiceLoader::LoadService(
-    ServiceManager* manager,
-    const GURL& url,
-    ScopedMessagePipeHandle shell_handle) {
+void NetworkServiceLoader::Load(ServiceManager* manager,
+                                const GURL& url,
+                                scoped_refptr<LoadCallbacks> callbacks) {
+  ScopedMessagePipeHandle shell_handle = callbacks->RegisterApplication();
+  if (!shell_handle.is_valid())
+    return;
+
   uintptr_t key = reinterpret_cast<uintptr_t>(manager);
   if (apps_.find(key) == apps_.end()) {
     scoped_ptr<ApplicationImpl> app(