Uses mojom module names as Dart's package: import URI

mojo/dart/embedder/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # embedder specific template rules.
 import("embedder.gni")
 
 source_set("dart_controller_no_snapshot") {
   sources = [
     "$target_gen_dir/dart_embedder_patch_resources.cc",
@@ skipping 58 matching lines @@
   deps = [
     ":dart_embedder_package_sdk",
     ":dart_embedder_package_application",
     ":dart_embedder_package_bindings",
     ":dart_embedder_package_network_service",
   ]
 }
 
 dart_embedder_package("dart_embedder_package_application") {
   package = "mojo/public/interfaces/application"
+  destination = "mojo"
 }
 
 dart_embedder_package("dart_embedder_package_bindings") {
   package = "mojo/public/interfaces/bindings"
+  destination = "mojo"
 }
 
 dart_embedder_package("dart_embedder_package_network_service") {
   package = "mojo/services/network/public/interfaces"
+  destination = "mojo"
 }
 
 action_foreach("dart_embedder_package_sdk") {
   sources = [
     "//mojo/public/dart/application.dart",
     "//mojo/public/dart/bindings.dart",
     "//mojo/public/dart/core.dart",
     "//mojo/public/dart/internal.dart",
     "//mojo/public/dart/src/application.dart",
     "//mojo/public/dart/src/application_connection.dart",
@@ skipping 213 matching lines @@
           "$root_gen_dir/dart_embedder_packages/mojo/public/dart/application.dart")
   embedder_package_bindings_path =
       rebase_path(
           "$root_gen_dir/dart_embedder_packages/mojo/public/dart/bindings.dart")
   embedder_package_core_path =
       rebase_path(
           "$root_gen_dir/dart_embedder_packages/mojo/public/dart/core.dart")
   url_mappings_script =
       rebase_path("//mojo/dart/embedder/tools/dart_embedder_url_mappings.py")
 
+  application_mojoms = rebase_path("//mojo/public/interfaces/application")
+  bindings_mojoms = rebase_path("//mojo/public/interfaces/bindings")
+  network_service_mojoms =
+      rebase_path("//mojo/services/network/public/interfaces")
+
   # This script generates --url_mapping command line arguments for all
   # generated mojom.dart bindings files. See HACKING.md for more information.
   embedder_mojom_url_mappings =
       exec_script(url_mappings_script,
                   [
-                    # Imports are relative to source tree root.
-                    rebase_path("//"),
-
                     # File system path containing target imports.
                     rebase_path("$root_gen_dir/dart_embedder_packages"),
 
                     # Embedder package directories.
-                    rebase_path("//mojo/public/interfaces/application"),
-                    rebase_path("//mojo/public/interfaces/bindings"),
-                    rebase_path("//mojo/services/network/public/interfaces"),
+                    "$application_mojoms,mojo",
+                    "$bindings_mojoms,mojo",
+                    "$network_service_mojoms,mojo",
                   ],
                   "list lines")
 
   args = [
            "--executable",
            rebase_path("$gen_snapshot_dir/gen_snapshot"),
            "--package_root",
-           rebase_path("$root_gen_dir"),
+           rebase_path("$root_gen_dir/dart-gen"),
            "--script",
            rebase_path("snapshot.dart"),
            "--vm_output_bin",
            rebase_path(vm_isolate_snapshot, root_build_dir),
            "--output_bin",
            rebase_path(isolate_snapshot, root_build_dir),
            "--target_os",
            os,
            "--url_mapping=dart:mojo.builtin,$builtin_path",
            "--url_mapping=dart:mojo.internal,$internal_path",
@@ skipping 27 matching lines @@
     "--vm_input_bin",
     rebase_path("$target_gen_dir/vm_isolate_snapshot.bin"),
     "--input_bin",
     rebase_path("$target_gen_dir/isolate_snapshot.bin"),
     "--input_cc",
     rebase_path("//mojo/dart/embedder/snapshot.cc.tmpl"),
     "--output",
     rebase_path(output),
   ]
 }