Move directory creation functions to base namespace.

net/base/directory_lister_unittest.cc

Index: net/base/directory_lister_unittest.cc
diff --git a/net/base/directory_lister_unittest.cc b/net/base/directory_lister_unittest.cc
index 0ad71af827c46dfad088359382dd7510c47d730e..0be09a5d7b4ce8c3d58d2c1b9dbe9e3621ec1726 100644
--- a/net/base/directory_lister_unittest.cc
+++ b/net/base/directory_lister_unittest.cc
@@ -122,7 +122,7 @@ class DirectoryListerTest : public PlatformTest {
         for (int i = 0; i < kBranchingFactor; i++) {
           std::string dir_name = base::StringPrintf("child_dir_%d", i);
           base::FilePath dir_path = dir_data.first.AppendASCII(dir_name);
-          ASSERT_TRUE(file_util::CreateDirectory(dir_path));
+          ASSERT_TRUE(base::CreateDirectory(dir_path));
           directories.push_back(std::make_pair(dir_path, dir_data.second + 1));
         }
       }