Remove gamma field from SkDeviceProperties

src/core/SkDeviceProperties.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkDeviceProperties_DEFINED
 #define SkDeviceProperties_DEFINED
 
 #include "SkSurfacePriv.h"
 
 struct SkDeviceProperties {
     SkDeviceProperties(const SkDeviceProperties& src) 
-        : fGamma(src.fGamma)
-        , fUseDFT(src.fUseDFT)
+        : fUseDFT(src.fUseDFT)
         , fPixelGeometry(src.fPixelGeometry) {
     }
 
-    SkDeviceProperties(float gamma = SK_GAMMA_EXPONENT)
-        : fGamma(gamma)
-        , fUseDFT(false)
+    SkDeviceProperties()
+        : fUseDFT(false)
         , fPixelGeometry(SkSurfacePropsDefaultPixelGeometry())
     {}
 
-    SkDeviceProperties(SkPixelGeometry geo, bool useDFT = false, float gamma = SK_GAMMA_EXPONENT)
-        : fGamma(gamma)
-        , fUseDFT(useDFT)
+    SkDeviceProperties(SkPixelGeometry geo, bool useDFT = false)
+        : fUseDFT(useDFT)
         , fPixelGeometry(geo)
     {}
 
-    float gamma() const { return fGamma; }
     bool useDFT() const { return fUseDFT; }
     SkPixelGeometry pixelGeometry() const { return fPixelGeometry; }
 
     void setPixelGeometry(SkPixelGeometry geo) {
         fPixelGeometry = geo;
     }
 
 private:
-    const float     fGamma;
     const bool      fUseDFT;
     SkPixelGeometry fPixelGeometry;
 };
 
 #endif