Use 1.25 DSF for 150~180 DPI

ash/display/display_change_observer_chromeos.h

 // Copyright 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_CHANGE_OBSERVER_CHROMEOS_H
 #define ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H
 
 #include "ash/ash_export.h"
 #include "ash/shell_observer.h"
 #include "base/basictypes.h"
@@ skipping 22 matching lines @@
   virtual bool GetResolutionForDisplayId(int64 display_id,
                                          gfx::Size* size) const OVERRIDE;
 
   // Overriden from ui::DisplayConfigurator::Observer:
   virtual void OnDisplayModeChanged(
       const ui::DisplayConfigurator::DisplayStateList& outputs) OVERRIDE;
 
   // Overriden from ShellObserver:
   virtual void OnAppTerminating() OVERRIDE;
 
+  // Exposed for testing.
+  ASH_EXPORT static float FindDeviceScaleFactor(float dpi);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(DisplayChangeObserver);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_AURA_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H