Testing: Fixed printing FilePaths when a test fails comparing them.

base/files/file_path_unittest.cc

Index: base/files/file_path_unittest.cc
diff --git a/base/files/file_path_unittest.cc b/base/files/file_path_unittest.cc
index c16293861ce7a6b6d94a6f6304486cae274b05a6..688c7eb39107da73d8eddfd21e4498dc7983a3f2 100644
--- a/base/files/file_path_unittest.cc
+++ b/base/files/file_path_unittest.cc
@@ -2,6 +2,8 @@
 // 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"
@@ -1273,4 +1275,13 @@ TEST_F(FilePathTest, ContentUriTest) {
 }
 #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("foo");
+  base::PrintTo(fp, &ss);
+  EXPECT_EQ("foo", ss.str());
+}
+
 }  // namespace base