Make sure that Content Handled application can be connected multiple times.

mojo/shell/network_application_loader.cc

Index: mojo/shell/network_application_loader.cc
diff --git a/mojo/shell/network_application_loader.cc b/mojo/shell/network_application_loader.cc
index dbe70b767c00fd1fef0950fe1d5852a517da7fc9..3d1bb85ee878dca13c2447a51aa888c60e4fee48 100644
--- a/mojo/shell/network_application_loader.cc
+++ b/mojo/shell/network_application_loader.cc
@@ -31,11 +31,9 @@ NetworkApplicationLoader::~NetworkApplicationLoader() {
 
 void NetworkApplicationLoader::Load(ApplicationManager* manager,
                                     const GURL& url,
+                                    ScopedMessagePipeHandle shell_handle,
                                     scoped_refptr<LoadCallbacks> callbacks) {
-  ScopedMessagePipeHandle shell_handle = callbacks->RegisterApplication();
-  if (!shell_handle.is_valid())
-    return;
-
+  DCHECK(shell_handle.is_valid());
   uintptr_t key = reinterpret_cast<uintptr_t>(manager);
   if (apps_.find(key) == apps_.end()) {
     scoped_ptr<ApplicationImpl> app(