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

ash/display/root_window_transformers.cc

 // Copyright (c) 2013 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/display/root_window_transformers.h"
 
 #include <cmath>
 
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
@@ skipping 11 matching lines @@
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/transform.h"
 #include "ui/gfx/transform.h"
 
 DECLARE_WINDOW_PROPERTY_TYPE(gfx::Display::Rotation);
 
 namespace ash {
 namespace internal {
 namespace {
 
+#if defined(OS_WIN)
 DEFINE_WINDOW_PROPERTY_KEY(gfx::Display::Rotation, kRotationPropertyKey,
                            gfx::Display::ROTATE_0);
+#endif
 
 // Round near zero value to zero.
 void RoundNearZero(gfx::Transform* transform) {
   const float kEpsilon = 0.001f;
   SkMatrix44& matrix = transform->matrix();
   for (int x = 0; x < 4; ++x) {
     for (int y = 0; y < 4; ++y) {
       if (std::abs(SkMScalarToFloat(matrix.get(x, y))) < kEpsilon)
         matrix.set(x, y, SkFloatToMScalar(0.0f));
     }
@@ skipping 238 matching lines @@
 
 aura::RootWindowTransformer* CreateRootWindowTransformerForMirroredDisplay(
     const DisplayInfo& source_display_info,
     const DisplayInfo& mirror_display_info) {
   return new MirrorRootWindowTransformer(source_display_info,
                                          mirror_display_info);
 }
 
 }  // namespace internal
 }  // namespace ash