Fixed all unused-variable Clang warnings on Windows.

ui/gfx/win/dpi.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 "ui/gfx/win/dpi.h"
 
 #include <windows.h>
 #include "base/win/scoped_hdc.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 
 namespace {
 
-int kDefaultDPIX = 96;
-int kDefaultDPIY = 96;
-
-bool force_highdpi_for_testing = false;
+int kDefaultDPI = 96;
 
 float g_device_scale_factor = 0.0f;
 
 float GetUnforcedDeviceScaleFactor() {
   // If the global device scale factor is initialized use it. This is to ensure
   // we use the same scale factor across all callsites.
   if (g_device_scale_factor)
     return g_device_scale_factor;
   return static_cast<float>(gfx::GetDPI().width()) /
-      static_cast<float>(kDefaultDPIX);
+      static_cast<float>(kDefaultDPI);
 }
 
 }  // namespace
 
 namespace gfx {
 
 void InitDeviceScaleFactor(float scale) {
   DCHECK_NE(0.0f, scale);
   g_device_scale_factor = scale;
 }
@@ skipping 62 matching lines @@
   // Always ceil sizes. Otherwise we may be leaving off part of the bounds.
   return ToCeiledSize(ScaleSize(dip_size, GetDPIScale()));
 }
 
 int GetSystemMetricsInDIP(int metric) {
   return static_cast<int>(GetSystemMetrics(metric) / GetDPIScale() + 0.5);
 }
 
 }  // namespace win
 }  // namespace gfx