Update Windows UI on system color changes.

ui/views/linux_ui/linux_ui.h

Index: ui/views/linux_ui/linux_ui.h
diff --git a/ui/views/linux_ui/linux_ui.h b/ui/views/linux_ui/linux_ui.h
index de9a566124b360735f44b6d52d3063e6f0627bb3..504de81a9ba8a4a53c86c617745419fa1f245403 100644
--- a/ui/views/linux_ui/linux_ui.h
+++ b/ui/views/linux_ui/linux_ui.h
@@ -36,7 +36,6 @@ namespace views {
 class Border;
 class LabelButton;
 class View;
-class NativeThemeChangeObserver;
 class WindowButtonOrderObserver;
 
 // Adapter class with targets to render like different toolkits. Set by any
@@ -138,12 +137,6 @@ class VIEWS_EXPORT LinuxUI : public ui::LinuxInputMethodContextFactory,
   virtual void RemoveWindowButtonOrderObserver(
       WindowButtonOrderObserver* observer) = 0;
 
-  // Notifies the observer when the native theme changes.
-  virtual void AddNativeThemeChangeObserver(
-      NativeThemeChangeObserver* observer) = 0;
-  virtual void RemoveNativeThemeChangeObserver(
-      NativeThemeChangeObserver* observer) = 0;
-
   // Determines whether the user's window manager is Unity.
   virtual bool UnityIsRunning() = 0;