Move unique name generation and tracking into //content.

content/public/test/test_runner_support.h

Index: content/public/test/test_runner_support.h
diff --git a/content/public/test/test_runner_support.h b/content/public/test/test_runner_support.h
new file mode 100644
index 0000000000000000000000000000000000000000..12c32d74605872ce1468fd061c70a624798a3b55
--- /dev/null
+++ b/content/public/test/test_runner_support.h
@@ -0,0 +1,21 @@
+// 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.
+
+#ifndef CONTENT_PUBLIC_TEST_TEST_RUNNER_SUPPORT_H_
+#define CONTENT_PUBLIC_TEST_TEST_RUNNER_SUPPORT_H_
+
+#include <string>
+
+namespace blink {
+class WebLocalFrame;
+}
+
+namespace content {
+
+// Returns the unique name associated with the given frame.
+std::string GetUniqueNameForFrame(blink::WebLocalFrame* frame);
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_TEST_TEST_RUNNER_SUPPORT_H_