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

chrome/browser/chromeos/display/overscan_calibrator.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 "chrome/browser/chromeos/display/overscan_calibrator.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "base/callback.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/canvas.h"
 
 namespace chromeos {
 namespace {
 
-// The opacity for the grey out borders.
-const float kBorderOpacity = 0.5;
-
 // The opacity for the arrows of the overscan calibration.
 const float kArrowOpacity = 0.8;
 
 // The height in pixel for the arrows to show the overscan calibration.
 const int kCalibrationArrowHeight = 50;
 
 // The gap between the boundary and calibration arrows.
 const int kArrowGapWidth = 20;
 
 // Draw the arrow for the overscan calibration to |canvas|.
@@ skipping 105 matching lines @@
     float device_scale_factor) {
   // TODO(mukai): Cancel the overscan calibration when the device
   // configuration has changed.
 }
 
 base::Closure OverscanCalibrator::PrepareForLayerBoundsChange() {
   return base::Closure();
 }
 
 }  // namespace chromeos