Enable hidpi on Linux, refactor a bit on Windows to share

ui/gfx/dpi.h

 // 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.
 
-#ifndef UI_GFX_DPI_WIN_H_
-#define UI_GFX_DPI_WIN_H_
+#ifndef UI_GFX_DPI_H_
+#define UI_GFX_DPI_H_
 
 #include "ui/gfx/gfx_export.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 namespace gfx {
 
 // Initialization of the scale factor that should be applied for rendering
 // in this process. Must be called before attempts to call any of the getter
 // methods below in this file, e.g. in the early toolkit/resource bundle setup.
 // This can be called multiple times during various tests, but subsequent calls
 // have no effect.
 GFX_EXPORT void InitDeviceScaleFactor(float scale);
 
+GFX_EXPORT float GetDeviceScaleFactor();
+
+// Returns true if the global device scale factor has been explicitly set for
+// the process.
+GFX_EXPORT bool IsDeviceScaleFactorSet();
+
+GFX_EXPORT void ForceHighDPISupportForTesting(float scale);
+
+GFX_EXPORT bool IsInHighDPIMode();
+
 GFX_EXPORT Size GetDPI();
 
 // Gets the scale factor of the display. For example, if the display DPI is
 // 96 then the scale factor is 1.0.
 GFX_EXPORT float GetDPIScale();
 
-// Tests to see if the command line flag "--high-dpi-support" is set.
-GFX_EXPORT bool IsHighDPIEnabled();
-
-GFX_EXPORT bool IsInHighDPIMode();
-
-GFX_EXPORT void EnableHighDPISupport();
-
-GFX_EXPORT void ForceHighDPISupportForTesting(float scale);
-
-// TODO(kevers|girard):  Move above methods into win namespace.
-
-namespace win {
-
-GFX_EXPORT float GetDeviceScaleFactor();
-
 GFX_EXPORT Point ScreenToDIPPoint(const Point& pixel_point);
 
 GFX_EXPORT Point DIPToScreenPoint(const Point& dip_point);
 
 // WARNING: there is no right way to scale sizes and rects. The implementation
 // of these strives to maintain a constant size by scaling the size independent
 // of the origin. An alternative is to get the enclosing rect, which is the
 // right way for some situations. Understand which you need before blindly
 // assuming this is the right way.
 GFX_EXPORT Rect ScreenToDIPRect(const Rect& pixel_bounds);
 GFX_EXPORT Rect DIPToScreenRect(const Rect& dip_bounds);
 GFX_EXPORT Size ScreenToDIPSize(const Size& size_in_pixels);
 GFX_EXPORT Size DIPToScreenSize(const Size& dip_size);
 
+// Tests to see if the command line flag "--high-dpi-support" is set on Windows,
+// always true on Linux.
+GFX_EXPORT bool IsHighDPIEnabled();
+
+#if defined(OS_WIN)
+namespace win {
+
+GFX_EXPORT void EnableHighDPISupport();
+
 // Win32's GetSystemMetrics uses pixel measures. This function calls
 // GetSystemMetrics for the given |metric|, then converts the result to DIP.
 GFX_EXPORT int GetSystemMetricsInDIP(int metric);
 
-// Returns true if the global device scale factor has been explicitly set for
-// the process.
-GFX_EXPORT bool IsDeviceScaleFactorSet();
+}  // namespace win
+#endif  // OS_WIN
 
-GFX_EXPORT extern const wchar_t kRegistryProfilePath[];
-GFX_EXPORT extern const wchar_t kHighDPISupportW[];
-
-}  // namespace win
 }  // namespace gfx
 
-#endif  // UI_GFX_DPI_WIN_H_
+#endif  // UI_GFX_DPI_H_