Dart: Changes to support building for Android.

services/dart/BUILD.gn

Index: services/dart/BUILD.gn
diff --git a/services/dart/BUILD.gn b/services/dart/BUILD.gn
index 4ac795e674d12d88ef542add8970fbb6275a9e4c..fd2933582f2feb7b460d6e190d74aeab33bfa384 100644
--- a/services/dart/BUILD.gn
+++ b/services/dart/BUILD.gn
@@ -12,7 +12,7 @@ group("dart") {
 
 action("generate_snapshot_bin") {
   deps = [
-    "//dart/runtime/bin:gen_snapshot",
+    "//dart/runtime/bin:gen_snapshot($host_toolchain)",
     "//mojo/public/interfaces/application",
   ]
   inputs = [
@@ -45,13 +45,15 @@ action("generate_snapshot_bin") {
     output,
   ]
 
+  gen_snapshot_dir = get_label_info(
+      "//dart/runtime/bin:gen_snapshot($host_toolchain)", "root_out_dir")
   script = "//dart/runtime/tools/create_snapshot_bin.py"
   application_path = rebase_path("//mojo/public/dart/application.dart")
   builtin_path = rebase_path("//mojo/dart/embedder/builtin.dart")
   bindings_path = rebase_path("//mojo/public/dart/bindings.dart")
   core_path = rebase_path("//mojo/public/dart/core.dart")
   args = [
-    "--executable", rebase_path("$root_out_dir/gen_snapshot"),
+    "--executable", rebase_path("$gen_snapshot_dir/gen_snapshot"),
     "--package_root", rebase_path("$root_gen_dir"),
     "--script", rebase_path("snapshot.dart"),
     "--output_bin", rebase_path(output, root_build_dir),