Pass application ids via AcceptConnection & ConnectToApplication callback.

mojo/shell/package_manager/package_manager_impl.cc

Index: mojo/shell/package_manager/package_manager_impl.cc
diff --git a/mojo/shell/package_manager/package_manager_impl.cc b/mojo/shell/package_manager/package_manager_impl.cc
index 93bbe85e75e7169162b785efdbccb61e1aa7e0a7..84a0e59ea73209d19f3d14bc615ce4372e4eb1ab 100644
--- a/mojo/shell/package_manager/package_manager_impl.cc
+++ b/mojo/shell/package_manager/package_manager_impl.cc
@@ -129,7 +129,7 @@ uint32_t PackageManagerImpl::HandleWithContentHandler(
                                  std::move(response));
     return connection->id();
   }
-  return Shell::kInvalidContentHandlerID;
+  return Shell::kInvalidApplicationID;
 }
 
 GURL PackageManagerImpl::ResolveURL(const GURL& url) {