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

mojo/shell/context.cc

Index: mojo/shell/context.cc
diff --git a/mojo/shell/context.cc b/mojo/shell/context.cc
index e1c742a8b670f734c1b825429644bb97948e8eff..b5238f9fba77771b8b7e1e0e23cfd1b2fbd46488 100644
--- a/mojo/shell/context.cc
+++ b/mojo/shell/context.cc
@@ -138,10 +138,10 @@ class Context::NativeViewportApplicationLoader
   // ApplicationLoader implementation.
   virtual void Load(ApplicationManager* manager,
                     const GURL& url,
-                    scoped_refptr<LoadCallbacks> callbacks) override {
-    ScopedMessagePipeHandle shell_handle = callbacks->RegisterApplication();
-    if (shell_handle.is_valid())
-      app_.reset(new ApplicationImpl(this, shell_handle.Pass()));
+                    ScopedMessagePipeHandle shell_handle,
+                    LoadCallback callbacks) override {
+    DCHECK(shell_handle.is_valid());
+    app_.reset(new ApplicationImpl(this, shell_handle.Pass()));
   }
 
   virtual void OnApplicationError(ApplicationManager* manager,