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

mojo/dart/embedder/test/dart_to_cpp_tests.cc

 // 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.
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 285 matching lines @@
                .AppendASCII("test")
                .AppendASCII(test);
 
     // Read in the source.
     std::string source;
     EXPECT_TRUE(ReadFileToString(path, &source)) << "Failed to read test file";
 
     // Setup the package root.
     base::FilePath package_root;
     PathService::Get(base::DIR_EXE, &package_root);
-    package_root = package_root.AppendASCII("gen");
+    package_root = package_root.AppendASCII("gen")
+                               .AppendASCII("dart-gen");
 
     config->strict_compilation = true;
     config->script = source;
     config->script_uri = path.AsUTF8Unsafe();
     config->package_root = package_root.AsUTF8Unsafe();
     config->application_data = nullptr;
     config->callbacks.exception =
         base::Bind(&UnhandledExceptionCallback, unhandled_exception);
     config->entropy = GenerateEntropy;
     config->handle = handle;
@@ skipping 55 matching lines @@
 TEST_F(DartToCppTest, Echo) {
   EchoCppSideConnection cpp_side_connection;
   bool unhandled_exception =
       RunTest("dart_to_cpp_tests.dart", &cpp_side_connection);
   EXPECT_TRUE(cpp_side_connection.DidSucceed());
   EXPECT_FALSE(unhandled_exception);
 }
 
 }  // namespace dart
 }  // namespace mojo