Record metric for dark mode status on desktop

Bug: 963939
Change-Id: Id1cc3f4e10fe3dde7b42b820b3821d26cb39aaca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1653841
Commit-Queue: Leonard Grey <[email protected]>
Reviewed-by: Ilya Sherman <[email protected]>
Reviewed-by: Elly Fong-Jones <[email protected]>
Cr-Commit-Position: refs/heads/master@{#668893}
diff --git a/ui/native_theme/native_theme.cc b/ui/native_theme/native_theme.cc
index 44e4aca4..bffca9c 100644
--- a/ui/native_theme/native_theme.cc
+++ b/ui/native_theme/native_theme.cc
@@ -48,6 +48,10 @@
   return is_dark_mode_;
 }
 
+bool NativeTheme::SystemDarkModeSupported() const {
+  return false;
+}
+
 bool NativeTheme::UsesHighContrastColors() const {
   return is_high_contrast_;
 }