Update from https://crrev.com/333737

base/files/file_path_unittest.cc

 // 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.
 
+#include <sstream>
+
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 // This macro helps avoid wrapped lines in the test structs.
 #define FPL(x) FILE_PATH_LITERAL(x)
 
 // This macro constructs strings which can contain NULs.
@@ skipping 1251 matching lines @@
 
   for (size_t i = 0; i < arraysize(cases); ++i) {
     FilePath input(cases[i].input);
     bool observed = input.IsContentUri();
     EXPECT_EQ(cases[i].expected, observed) <<
               "i: " << i << ", input: " << input.value();
   }
 }
 #endif
 
+// Test the PrintTo overload for FilePath (used when a test fails to compare two
+// FilePaths).
+TEST_F(FilePathTest, PrintTo) {
+  std::stringstream ss;
+  FilePath fp(FPL("foo"));
+  base::PrintTo(fp, &ss);
+  EXPECT_EQ("foo", ss.str());
+}
+
 }  // namespace base