mus: Introduce high-contrast mode in mus.

services/ui/ws/platform_display.cc

Index: services/ui/ws/platform_display.cc
diff --git a/services/ui/ws/platform_display.cc b/services/ui/ws/platform_display.cc
index 801a8a4c9757a063e31e4268c32745aba3f5b357..93d4e08831f4dd5a92a45bd8530ea88dc3332cf7 100644
--- a/services/ui/ws/platform_display.cc
+++ b/services/ui/ws/platform_display.cc
@@ -271,6 +271,10 @@ void DefaultPlatformDisplay::OnCompositorFrameDrawn() {
     delegate_->OnCompositorFrameDrawn();
 }
 
+bool DefaultPlatformDisplay::IsInHighContrastMode() {
+  return delegate_ ? delegate_->IsInHighContrastMode() : false;
+}
+
 const ViewportMetrics& DefaultPlatformDisplay::GetViewportMetrics() {
   return metrics_;
 }