gfx: Converge scale precision related differences to single class.

ui/gfx/switches.cc

Index: ui/gfx/switches.cc
diff --git a/ui/gfx/switches.cc b/ui/gfx/switches.cc
index 6e7147ee2fc6ff4ead0c8ca8f18679ca2f98e6fd..4e370ae2741ee2741cfcc38bc25d8c6155202499 100644
--- a/ui/gfx/switches.cc
+++ b/ui/gfx/switches.cc
@@ -9,6 +9,11 @@ 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";