Introduce user customization of external HighDPI mode for 4K monitor.

ash/display/display_info.h

 // 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.
 
 #ifndef ASH_DISPLAY_DISPLAY_INFO_H_
 #define ASH_DISPLAY_DISPLAY_INFO_H_
 
 #include <string>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "ui/display/types/display_constants.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/rect.h"
 
 namespace ash {
 
 // A struct that represents the display's mode info.
 struct ASH_EXPORT DisplayMode {
   DisplayMode();
   DisplayMode(const gfx::Size& size,
               float refresh_rate,
               bool interlaced,
               bool native);
 
+  // Returns the size in DIP which isvisible to the user.
+  gfx::Size GetSizeInDIP() const;
+
+  // Returns true if |other| has same size and scale factors.
+  bool IsEquivalent(const DisplayMode& other) const;
+
   gfx::Size size;      // Physical pixel size of the display.
   float refresh_rate;  // Refresh rate of the display, in Hz.
   bool interlaced;     // True if mode is interlaced.
   bool native;         // True if mode is native mode of the display.
+  float ui_scale;      // The UI scale factor of the mode.
+  float device_scale_factor;  // The device scale factor of the mode.
 };
 
 // DisplayInfo contains metadata for each display. This is used to
 // create |gfx::Display| as well as to maintain extra infomation
 // to manage displays in ash environment.
 // This class is intentionally made copiable.
 class ASH_EXPORT DisplayInfo {
  public:
   // Creates a DisplayInfo from string spec. 100+200-1440x800 creates display
   // whose size is 1440x800 at the location (100, 200) in host coordinates.
@@ skipping 210 matching lines @@
   // The current profile of the color calibration.
   ui::ColorCalibrationProfile color_profile_;
 
   // The list of available variations for the color calibration.
   std::vector<ui::ColorCalibrationProfile> available_color_profiles_;
 };
 
 }  // namespace ash
 
 #endif  //  ASH_DISPLAY_DISPLAY_INFO_H_