linux and chromeos: Turn on -Wunused-const-variable.

ash/wm/system_background_controller.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/wm/system_background_controller.h"
 
 #include "ui/aura/root_window.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_type.h"
 
 namespace ash {
 namespace internal {
 
-namespace {
-
-#if defined(OS_CHROMEOS)
-// Background color used for the Chrome OS boot splash screen.
-const SkColor kChromeOsBootColor = SkColorSetARGB(0xff, 0xfe, 0xfe, 0xfe);
-#endif
-
-}  // namespace
-
 SystemBackgroundController::SystemBackgroundController(
     aura::RootWindow* root_window,
     SkColor color)
     : root_window_(root_window),
       layer_(new ui::Layer(ui::LAYER_SOLID_COLOR)) {
   root_window_->AddObserver(this);
   layer_->SetColor(color);
 
   ui::Layer* root_layer = root_window_->layer();
   layer_->SetBounds(gfx::Rect(root_layer->bounds().size()));
@@ skipping 12 matching lines @@
 void SystemBackgroundController::OnWindowBoundsChanged(
     aura::Window* root,
     const gfx::Rect& old_bounds,
     const gfx::Rect& new_bounds) {
   DCHECK_EQ(root_window_, root);
   layer_->SetBounds(gfx::Rect(root_window_->layer()->bounds().size()));
 }
 
 }  // namespace internal
 }  // namespace ash