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

mojo/dart/embedder/test/validation_unittest.cc

 // 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.
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 41 matching lines @@
              .AppendASCII("test")
              .AppendASCII("validation_test.dart");
 
   // 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");
 
   char* error = NULL;
   bool unhandled_exception = false;
   DartControllerConfig config;
   config.script = source;
   // Run with strict compilation even in Release mode so that ASAN testing gets
   // coverage of Dart asserts, type-checking, etc.
   config.strict_compilation = true;
   config.script_uri = test;
   config.package_root = package_root.AsUTF8Unsafe();
@@ skipping 12 matching lines @@
   EXPECT_FALSE(unhandled_exception);
 }
 
 TEST(DartTest, validation) {
   RunTest(GetPath());
 }
 
 }  // namespace
 }  // namespace dart
 }  // namespace mojo