add legacy/helper allocN32Pixels, and convert gm to use it

gm/mixedxfermodes.cpp

 
 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "gm.h"
 #include "SkBitmap.h"
 #include "SkRandom.h"
@@ skipping 66 matching lines @@
         }
     }
 
     virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
         if (NULL == fBG.get()) {
             static uint32_t kCheckerPixelData[] = { 0xFFFFFFFF,
                                                     0xFFCCCCCC,
                                                     0xFFCCCCCC,
                                                     0xFFFFFFFF };
             SkBitmap bitmap;
-            bitmap.setConfig(SkBitmap::kARGB_8888_Config, 2, 2, 2 * sizeof(uint32_t));
-            bitmap.allocPixels();
-            bitmap.lockPixels();
+            bitmap.allocN32Pixels(2, 2);
             memcpy(bitmap.getPixels(), kCheckerPixelData, sizeof(kCheckerPixelData));
-            bitmap.unlockPixels();
             fBG.reset(SkShader::CreateBitmapShader(bitmap,
                                                    SkShader::kRepeat_TileMode,
                                                    SkShader::kRepeat_TileMode));
         }
         SkMatrix lm;
         lm.setScale(SkIntToScalar(20), SkIntToScalar(20));
         fBG->setLocalMatrix(lm);
 
         SkPaint bgPaint;
         bgPaint.setShader(fBG.get());
@@ skipping 37 matching lines @@
     SkPath                 fConvexPath;
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new MixedXfermodesGM; }
 static GMRegistry reg(MyFactory);
 
 }