Move WriteFile and WriteFileDescriptor from file_util to base namespace.

ui/gfx/ozone/impl/file_surface_factory.cc

Index: ui/gfx/ozone/impl/file_surface_factory.cc
diff --git a/ui/gfx/ozone/impl/file_surface_factory.cc b/ui/gfx/ozone/impl/file_surface_factory.cc
index 1f440dbddf94b4edb4cc80b98a218fcd0781ff56..5d3d554e466798cf3712edd2aa388a5ebebd2ebc 100644
--- a/ui/gfx/ozone/impl/file_surface_factory.cc
+++ b/ui/gfx/ozone/impl/file_surface_factory.cc
@@ -20,9 +20,9 @@ void WriteDataToFile(const base::FilePath& location,
                      const SkBitmap& bitmap) {
   std::vector<unsigned char> png_data;
   gfx::PNGCodec::FastEncodeBGRASkBitmap(bitmap, true, &png_data);
-  file_util::WriteFile(location,
-                       (char*)vector_as_array(&png_data),
-                       png_data.size());
+  base::WriteFile(location,
+                  static_cast<const char*>(vector_as_array(&png_data)),
+                  png_data.size());
 }
 
 }