Remove pre-MD code from PowerStatusView.

ash/common/material_design/material_design_controller.h

Index: ash/common/material_design/material_design_controller.h
diff --git a/ash/common/material_design/material_design_controller.h b/ash/common/material_design/material_design_controller.h
index baaee6a425721a2b822bb5515069fc9d2319dff6..50159890e3e9e84166c53573e40bdc95a95585c8 100644
--- a/ash/common/material_design/material_design_controller.h
+++ b/ash/common/material_design/material_design_controller.h
@@ -19,9 +19,6 @@ class ASH_EXPORT MaterialDesignController {
   // Returns true.
   static bool IsSystemTrayMenuMaterial();
 
-  // Returns true.
-  static bool UseMaterialDesignSystemIcons();
-
  private:
   // Declarations only. Do not allow construction of an object.
   MaterialDesignController();