Move WriteFile and WriteFileDescriptor from file_util to base namespace.

base/mac/mac_util_unittest.mm

Index: base/mac/mac_util_unittest.mm
diff --git a/base/mac/mac_util_unittest.mm b/base/mac/mac_util_unittest.mm
index 1b56814abec936b9d605a446de25a86ed28c380b..079f3c2ced8bf495d483c334060cad213bb164cd 100644
--- a/base/mac/mac_util_unittest.mm
+++ b/base/mac/mac_util_unittest.mm
@@ -108,7 +108,7 @@ TEST_F(MacUtilTest, TestExcludeFileFromBackups) {
   const char dummy_data[] = "All your base are belong to us!";
   // Dump something real into the file.
   ASSERT_EQ(static_cast<int>(arraysize(dummy_data)),
-      file_util::WriteFile(dummy_file_path, dummy_data, arraysize(dummy_data)));
+            WriteFile(dummy_file_path, dummy_data, arraysize(dummy_data)));
   NSString* fileURLString =
       [NSString stringWithUTF8String:dummy_file_path.value().c_str()];
   NSURL* fileURL = [NSURL URLWithString:fileURLString];