Avoid copies in SkMasks constructor

src/codec/SkMasks.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodecPriv.h"
 #include "SkMasks.h"
 #include "SkTypes.h"
@@ skipping 50 matching lines @@
 static uint8_t get_comp(uint32_t pixel, uint32_t mask, uint32_t shift,
                         uint32_t size) {
     return convert_to_8((pixel & mask) >> shift, size);
 }
 
 /*
  *
  * Get a color component
  *
  */
-uint8_t SkMasks::getRed(uint32_t pixel) {
+uint8_t SkMasks::getRed(uint32_t pixel) const {
     return get_comp(pixel, fRed.mask, fRed.shift, fRed.size);
 }
-uint8_t SkMasks::getGreen(uint32_t pixel) {
+uint8_t SkMasks::getGreen(uint32_t pixel) const {
     return get_comp(pixel, fGreen.mask, fGreen.shift, fGreen.size);
 }
-uint8_t SkMasks::getBlue(uint32_t pixel) {
+uint8_t SkMasks::getBlue(uint32_t pixel) const {
     return get_comp(pixel, fBlue.mask, fBlue.shift, fBlue.size);
 }
-uint8_t SkMasks::getAlpha(uint32_t pixel) {
+uint8_t SkMasks::getAlpha(uint32_t pixel) const {
     return get_comp(pixel, fAlpha.mask, fAlpha.shift, fAlpha.size);
 }
 
 /*
  *
  * Process an input mask to obtain the necessary information
  *
  */
 const SkMasks::MaskInfo process_mask(uint32_t mask, uint32_t bpp) {
     // Trim the masks to the allowed number of bits
@@ skipping 54 matching lines @@
     // Collect information about the masks
     const MaskInfo red = process_mask(masks.red, bitsPerPixel);
     const MaskInfo green = process_mask(masks.green, bitsPerPixel);
     const MaskInfo blue = process_mask(masks.blue, bitsPerPixel);
     const MaskInfo alpha = process_mask(masks.alpha, bitsPerPixel);
 
     return new SkMasks(red, green, blue, alpha);
 }
 
 
-SkMasks::SkMasks(const MaskInfo red, const MaskInfo green,
-                 const MaskInfo blue, const MaskInfo alpha)
+SkMasks::SkMasks(const MaskInfo& red, const MaskInfo& green,
+                 const MaskInfo& blue, const MaskInfo& alpha)
     : fRed(red)
     , fGreen(green)
     , fBlue(blue)
     , fAlpha(alpha)
 {}