Dart: Put generated .mojom.dart files under mojoms pacakge.

mojo/dart/embedder/BUILD.gn

Index: mojo/dart/embedder/BUILD.gn
diff --git a/mojo/dart/embedder/BUILD.gn b/mojo/dart/embedder/BUILD.gn
index ef61af17976d325b7c107cf6c9e0c0a538a2f4dc..8c6aaac1252cf8e1c29028d5b2485b1eab3b97ce 100644
--- a/mojo/dart/embedder/BUILD.gn
+++ b/mojo/dart/embedder/BUILD.gn
@@ -76,17 +76,17 @@ group("dart_embedder_packages") {
 
 dart_embedder_package("dart_embedder_package_application") {
   package = "mojo/public/interfaces/application"
-  destination = "mojo"
+  destination = "mojoms/mojo"
 }
 
 dart_embedder_package("dart_embedder_package_bindings") {
   package = "mojo/public/interfaces/bindings"
-  destination = "mojo"
+  destination = "mojoms/mojo"
 }
 
 dart_embedder_package("dart_embedder_package_network_service") {
   package = "mojo/services/network/public/interfaces"
-  destination = "mojo"
+  destination = "mojoms/mojo"
 }
 
 action_foreach("dart_embedder_package_sdk") {
@@ -334,9 +334,9 @@ action("generate_snapshot_bin") {
                     rebase_path("$root_gen_dir/dart_embedder_packages"),
 
                     # Embedder package directories.
-                    "$application_mojoms,mojo",
-                    "$bindings_mojoms,mojo",
-                    "$network_service_mojoms,mojo",
+                    "$application_mojoms,mojoms/mojo",
+                    "$bindings_mojoms,mojoms/mojo",
+                    "$network_service_mojoms,mojoms/mojo",
                   ],
                   "list lines")