Fixed pass-by-value to pass-by-reference

ui/gfx/color_utils.cc

 // Copyright (c) 2011 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/color_utils.h"
 
 #include <math.h>
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
@@ skipping 224 matching lines @@
     g += cg;
     b += cb;
     ++color_count;
   }
 
   return color_count ?
       SkColorSetARGB(alpha, r / color_count, g / color_count, b / color_count) :
       SkColorSetARGB(alpha, 0, 0, 0);
 }
 
-void BuildLumaHistogram(SkBitmap* bitmap, int histogram[256]) {
-  SkAutoLockPixels bitmap_lock(*bitmap);
-  if (!bitmap->getPixels())
+void BuildLumaHistogram(const SkBitmap& bitmap, int histogram[256]) {
+  SkAutoLockPixels bitmap_lock(bitmap);
+  if (!bitmap.getPixels())
     return;
 
   // Assume ARGB_8888 format.
-  DCHECK(bitmap->getConfig() == SkBitmap::kARGB_8888_Config);
+  DCHECK(bitmap.getConfig() == SkBitmap::kARGB_8888_Config);
 
-  int pixel_width = bitmap->width();
-  int pixel_height = bitmap->height();
+  int pixel_width = bitmap.width();
+  int pixel_height = bitmap.height();
   for (int y = 0; y < pixel_height; ++y) {
-    SkColor* current_color = static_cast<uint32_t*>(bitmap->getAddr32(0, y));
+    SkColor* current_color = static_cast<uint32_t*>(bitmap.getAddr32(0, y));
     for (int x = 0; x < pixel_width; ++x, ++current_color)
       histogram[GetLuminanceForColor(*current_color)]++;
   }
 }
 
 SkColor AlphaBlend(SkColor foreground, SkColor background, SkAlpha alpha) {
   if (alpha == 0)
     return background;
   if (alpha == 255)
     return foreground;
@@ skipping 32 matching lines @@
 SkColor GetSysSkColor(int which) {
 #if defined(OS_WIN)
   return skia::COLORREFToSkColor(GetSysColor(which));
 #else
   NOTIMPLEMENTED();
   return SK_ColorLTGRAY;
 #endif
 }
 
 }  // namespace color_utils