Avoid copies in SkMasks constructor

src/codec/SkMasks.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkMasks_DEFINED
 #define SkMasks_DEFINED
 
 #include "SkTypes.h"
@@ skipping 34 matching lines @@
      * Create the masks object
      *
      */
     static SkMasks* CreateMasks(InputMasks masks, uint32_t bpp);
 
     /*
      *
      * Get a color component
      *
      */
-    uint8_t getRed(uint32_t pixel);
-    uint8_t getGreen(uint32_t pixel);
-    uint8_t getBlue(uint32_t pixel);
-    uint8_t getAlpha(uint32_t pixel);
+    uint8_t getRed(uint32_t pixel) const;
+    uint8_t getGreen(uint32_t pixel) const;
+    uint8_t getBlue(uint32_t pixel) const;
+    uint8_t getAlpha(uint32_t pixel) const;
 
     /*
      *
      * Getter for the alpha mask
      * The alpha mask may be used in other decoding modes
      *
      */
-     uint32_t getAlphaMask() {
+     uint32_t getAlphaMask() const {
         return fAlpha.mask;
      }
 
 private:
 
     /*
      *
-     * Constrcutor
+     * Constructor
      *
      */
-    SkMasks(const MaskInfo red, const MaskInfo green, const MaskInfo blue,
-            const MaskInfo alpha);
+    SkMasks(const MaskInfo& red, const MaskInfo& green, const MaskInfo& blue,
+            const MaskInfo& alpha);
 
     const MaskInfo fRed;
     const MaskInfo fGreen;
     const MaskInfo fBlue;
     const MaskInfo fAlpha;
 };
 
 #endif