Reduce flakiness in chrome_frame_tests.exe by having each run in a clean environment.

chrome_frame/test/test_scrubber.h

+// Copyright (c) 2012 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.
+
+// The test scrubber cleans up machine state between tests.  This includes
+// killing all Internet Explorer processes, killing all Chrome processes spawned
+// by Chrome Frame, and deleting the user data directory.  The scrubber must be
+// installed before tests are run via |InstallTestScrubber|.
+//
+// Tests that lead to Chrome using a user data directory other than that used by
+// Chrome Frame in IE must provide that directory to the scrubber via
+// |OverrideDataDirectoryForThisTest()|.  Failure to do so will lead to the
+// scrubber failing to delete that directory.
+
+#ifndef CHROME_FRAME_TEST_TEST_SCRUBBER_H_
+#define CHROME_FRAME_TEST_TEST_SCRUBBER_H_
+#pragma once
+
+#include "base/string_piece.h"
+
+namespace testing {
+class UnitTest;
+}
+
+namespace chrome_frame_test {
+
+// Install the scrubber in |unit_test| (call before RUN_ALL_TESTS).
+void InstallTestScrubber(testing::UnitTest* unit_test);
+
+// Override the user data directory that will be deleted by the scrubber at the
+// completion of the current test.
+void OverrideDataDirectoryForThisTest(const base::StringPiece16& user_data_dir);
+
+}  // namespace chrome_frame_test
+
+#endif  // CHROME_FRAME_TEST_TEST_SCRUBBER_H_