Migrate TestCommon to Chromium c++ style and remove un-used header.

content/shell/renderer/test_runner/TestCommon.h

-// Copyright 2013 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_SHELL_RENDERER_TEST_RUNNER_TESTCOMMON_H_
-#define CONTENT_SHELL_RENDERER_TEST_RUNNER_TESTCOMMON_H_
-
-#include <stdio.h>
-#include <string>
-
-#include "base/compiler_specific.h"
-
-#if defined(WIN32)
-#define snprintf(str, size, ...) _snprintf_s(str, size, size, __VA_ARGS__)
-#endif
-
-namespace content {
-
-inline bool isASCIIAlpha(char ch) { return (ch | 0x20) >= 'a' && (ch | 0x20) <= 'z'; }
-
-inline bool isNotASCIIAlpha(char ch) { return !isASCIIAlpha(ch); }
-
-std::string normalizeLayoutTestURL(const std::string& url);
-
-}  // namespace content
-
-#endif  // CONTENT_SHELL_RENDERER_TEST_RUNNER_TESTCOMMON_H_