replace setConfig+allocPixels with single call

tests/MipMapTest.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 "SkBitmap.h"
 #include "SkMipMap.h"
 #include "SkRandom.h"
 #include "Test.h"
 
 static void make_bitmap(SkBitmap* bm, SkRandom& rand) {
     // for now, Build needs a min size of 2, otherwise it will return NULL.
     // should fix that to support 1 X N, where N > 1 to return non-null.
     int w = 2 + rand.nextU() % 1000;
     int h = 2 + rand.nextU() % 1000;
-    bm->setConfig(SkBitmap::kARGB_8888_Config, w, h);
-    bm->allocPixels();
+    bm->allocN32Pixels(w, h);
     bm->eraseColor(SK_ColorWHITE);
 }
 
 DEF_TEST(MipMap, reporter) {
     SkBitmap bm;
     SkRandom rand;
 
     for (int i = 0; i < 500; ++i) {
         make_bitmap(&bm, rand);
         SkAutoTUnref<SkMipMap> mm(SkMipMap::Build(bm));
@@ skipping 17 matching lines @@
 
                 if (prevLevel.fPixels) {
                     REPORTER_ASSERT(reporter, level.fWidth <= prevLevel.fWidth);
                     REPORTER_ASSERT(reporter, level.fHeight <= prevLevel.fHeight);
                 }
                 prevLevel = level;
             }
         }
     }
 }