Add Toolbar test utility classes.

ios/shared/chrome/browser/ui/toolbar/BUILD.gn

Index: ios/shared/chrome/browser/ui/toolbar/BUILD.gn
diff --git a/ios/shared/chrome/browser/ui/toolbar/BUILD.gn b/ios/shared/chrome/browser/ui/toolbar/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..d787bd37d9cd8131e7df5d65baf16bb7ecef8f46
--- /dev/null
+++ b/ios/shared/chrome/browser/ui/toolbar/BUILD.gn
@@ -0,0 +1,15 @@
+# Copyright 2017 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.
+
+source_set("test_support") {
+  testonly = true
+  sources = [
+    "toolbar_test_util.h",
+    "toolbar_test_util.mm",
+  ]
+  deps = [
+    "//ios/web:test_support",
+  ]
+  configs += [ "//build/config/compiler:enable_arc" ]
+}