IWYU fixes in /ui/native_theme.

base/win/registry.h includes more than it uses. These files were
inadvertently relying on that fact. This CL adds missing includes so
that registry.h can be cleaned up.

BUG=None
This CL was uploaded by git cl split.

R=estade@chromium.org

Change-Id: I8640470b816fa9c012bd43594d90dce34e6a711e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2475055
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Auto-Submit: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817505}

ui/native_theme/native_theme_win.cc

@@ -11,6 +11,7 @@
 #include <vssym32.h>
 
 #include "base/bind.h"
+#include "base/callback.h"
 #include "base/check.h"
 #include "base/command_line.h"
 #include "base/notreached.h"