Dart: Changes to support building for Android.

mojo/dart/embedder/test/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.
 
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 
 action("generate_test_snapshot_bin") {
   deps = [
-    "//dart/runtime/bin:gen_snapshot",
+    "//dart/runtime/bin:gen_snapshot($host_toolchain)",
   ]
   inputs = [
     "test_snapshot.dart",
     "//dart/runtime/tools/create_snapshot_bin.py",
     "//mojo/dart/embedder/builtin.dart",
     "//mojo/public/dart/bindings.dart",
     "//mojo/public/dart/core.dart",
     "//mojo/public/dart/src/buffer.dart",
     "//mojo/public/dart/src/codec.dart",
     "//mojo/public/dart/src/data_pipe.dart",
     "//mojo/public/dart/src/drain_data.dart",
     "//mojo/public/dart/src/event_stream.dart",
     "//mojo/public/dart/src/handle.dart",
     "//mojo/public/dart/src/handle_watcher.dart",
     "//mojo/public/dart/src/message.dart",
     "//mojo/public/dart/src/message_pipe.dart",
     "//mojo/public/dart/src/proxy.dart",
     "//mojo/public/dart/src/struct.dart",
     "//mojo/public/dart/src/stub.dart",
     "//mojo/public/dart/src/timer_impl.dart",
     "//mojo/public/dart/src/timer_queue.dart",
     "//mojo/public/dart/src/types.dart",
   ]
   output = "$target_gen_dir/test_snapshot_gen.bin"
   outputs = [
     output,
   ]
 
+  gen_snapshot_dir = get_label_info(
+      "//dart/runtime/bin:gen_snapshot($host_toolchain)", "root_out_dir")
   script = "//dart/runtime/tools/create_snapshot_bin.py"
   builtin_path = rebase_path("//mojo/dart/embedder/builtin.dart")
   bindings_path = rebase_path("//mojo/public/dart/bindings.dart")
   core_path = rebase_path("//mojo/public/dart/core.dart")
   args = [
-    "--executable", rebase_path("$root_out_dir/gen_snapshot"),
+    "--executable", rebase_path("$gen_snapshot_dir/gen_snapshot"),
     "--package_root", rebase_path("$root_gen_dir"),
     "--script", rebase_path("test_snapshot.dart"),
     "--output_bin", rebase_path(output, root_build_dir),
     "--target_os", os,
     "--url_mapping=dart:mojo_bindings,$bindings_path",
     "--url_mapping=dart:mojo_builtin,$builtin_path",
     "--url_mapping=dart:mojo_core,$core_path",
   ]
 }
 
@@ skipping 78 matching lines @@
     "//mojo/public/interfaces/bindings/tests:test_interfaces",
     "//testing/gtest",
   ]
 }
 
 mojom("dart_to_cpp_bindings") {
   sources = [
     "dart_to_cpp.mojom",
   ]
 }