gfx: Converge scale precision related differences to single class.

ui/gfx/switches.cc

 // Copyright 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/switches.h"
 
 namespace switches {
 
 // Overrides the device scale factor for the browser UI and the contents.
 const char kForceDeviceScaleFactor[] = "force-device-scale-factor";
 
+// Enables fixed precision for scale factors, so that different scale factors
+// which are almost equal (differ by some threshold magnitude of floating point
+// epsilon) are considered as same.
+const char kEnableFixedPrecisionScale[] = "enable-fixed-precision-scale";
+
 #if defined(OS_WIN)
 // Disables the DirectWrite font rendering system on windows.
 const char kDisableDirectWrite[] = "disable-direct-write";
 
 // Disables DirectWrite font rendering for general UI elements.
 const char kDisableDirectWriteForUI[] = "disable-directwrite-for-ui";
 #endif
 
 #if defined(OS_MACOSX)
 // Enables the HarfBuzz port of RenderText on Mac (it's already used only for
 // text editing; this enables it for everything else).
 const char kEnableHarfBuzzRenderText[] = "enable-harfbuzz-rendertext";
 #endif
 
 }  // namespace switches