Update from https://crrev.com/333737

base/test/test_file_util.cc

 // 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.
 
 #include "base/test/test_file_util.h"
 
 #include "base/test/test_timeouts.h"
 #include "base/threading/platform_thread.h"
 
 namespace base {
 
 bool EvictFileFromSystemCacheWithRetry(const FilePath& path) {
   const int kCycles = 10;
   const TimeDelta kDelay = TestTimeouts::action_timeout() / kCycles;
   for (int i = 0; i < kCycles; i++) {
     if (EvictFileFromSystemCache(path))
       return true;
     PlatformThread::Sleep(kDelay);
   }
   return false;
 }
 
+// Declared in base/files/file_path.h.
+void PrintTo(const FilePath& path, std::ostream* out) {
+  *out << path.value();
+}
+
 }  // namespace base