base: Update the include paths of base/string_piece.h to its new location.

base/test/expectations/expectation.h

 // Copyright (c) 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 BASE_TEST_EXPECTATIONS_EXPECTATION_H_
 #define BASE_TEST_EXPECTATIONS_EXPECTATION_H_
 
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/compiler_specific.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 
 namespace test_expectations {
 
 // A Result is the expectation of a test's behavior.
 enum Result {
   // The test has a failing assertion.
   RESULT_FAILURE,
 
   // The test does not complete within the test runner's alloted duration.
   RESULT_TIMEOUT,
@@ skipping 61 matching lines @@
   // The build configuration.
   Configuration configuration;
 
   // The expected result of this test.
   Result result;
 };
 
 }  // namespace test_expectations
 
 #endif  // BASE_TEST_EXPECTATIONS_EXPECTATION_H_