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

mojo/dart/embedder/embedder.gni

 # Copyright 2015 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.
 
 # Template to generate a dart embedder package.
 # Required invoker inputs:
 #   String package (relative path to package e.g. mojo/public/interfaces/application)
 template("dart_embedder_package") {
   package = invoker.package
   package_path = "//$package"
 
+  destination = package
+  if (defined(invoker.destination)) {
+    destination = invoker.destination
+  }
+
   action_foreach(target_name) {
     deps = [
       package_path,
     ]
     list_generated_bindings_script =
         rebase_path(
             "//mojo/dart/embedder/tools/dart_list_generated_bindings.py")
     root_prefix = rebase_path("//")
     source_directory = rebase_path(package_path)
     generated_bindings = exec_script(list_generated_bindings_script,
                                      [
                                        source_directory,
                                        root_prefix,
                                      ],
                                      "list lines")
     sources = rebase_path(generated_bindings, ".", root_gen_dir)
     outputs = [
-      "$root_gen_dir/dart_embedder_packages/$package/{{source_file_part}}",
+      "$root_gen_dir/dart_embedder_packages/$destination/{{source_file_part}}",
     ]
     script = rebase_path(
             "//mojo/dart/embedder/tools/dart_rewrite_embedder_package_imports.py")
     args = [
       rebase_path("{{source}}", "", root_build_dir),
       rebase_path(
-          "$root_gen_dir/dart_embedder_packages/$package/{{source_file_part}}"),
+          "$root_gen_dir/dart_embedder_packages/$destination/{{source_file_part}}"),
     ]
   }
 }
 
 # Template to generate a dart embedder resource.cc file.
 # Required invoker inputs:
 #   String output (name of output file)
 #   List inputs (list of input files to be included)
 #   String table_name (name of symbol for resource table)
 # Optional invoker inputs:
@@ skipping 33 matching lines @@
     ]
     if (defined(invoker.input_directory)) {
       args += [
         "--client_root",
         rebase_path(invoker.input_directory),
       ]
     }
     args += rebase_path(invoker.inputs)
   }
 }