Add our own (mojo::util::)ScopedFILE and replace uses of base::ScopedFILE with it.

mojo/edk/util/BUILD.gn

Index: mojo/edk/util/BUILD.gn
diff --git a/mojo/edk/util/BUILD.gn b/mojo/edk/util/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..455a6c67d56e33c9705f6ef5e8fa01df4feaa4f5
--- /dev/null
+++ b/mojo/edk/util/BUILD.gn
@@ -0,0 +1,22 @@
+# Copyright 2015 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.
+
+import("../mojo_edk.gni")
+
+mojo_edk_source_set("util") {
+  sources = [
+    "scoped_file.h",
+  ]
+
+  defines = [
+    "MOJO_SYSTEM_IMPL_IMPLEMENTATION",
+    "MOJO_SYSTEM_IMPLEMENTATION",
+  ]
+
+  mojo_edk_configs = [ "mojo/edk/system:system_config" ]
+
+  deps = [
+    "//base",
+  ]
+}