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

gm/bitmappremul.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 "SkCanvas.h"
 #include "SkColorPriv.h"
 
 /**
  * This GM checks that bitmap pixels are unpremultiplied before being exported
  * to other formats. If unpremultiplication is implemented properly, this
  * GM should come out completely white. If not, this GM looks like a row of two
  * greyscale gradients above a row of grey lines.
  * This tests both the ARGB4444 and ARGB8888 bitmap configurations.
  */
 
 static const int SLIDE_SIZE = 256;
 static const int PIXEL_SIZE_8888 = SLIDE_SIZE / 256;
 static const int PIXEL_SIZE_4444 = SLIDE_SIZE / 16;
 
 static void init_bitmap(SkBitmap::Config config, SkBitmap* bitmap) {
-    bitmap->setConfig(config, SLIDE_SIZE, SLIDE_SIZE);
-    bitmap->allocPixels();
+    bitmap->allocConfigPixels(config, SLIDE_SIZE, SLIDE_SIZE);
     bitmap->eraseColor(SK_ColorWHITE);
 }
 
 static SkBitmap make_argb8888_gradient() {
     SkBitmap bitmap;
     init_bitmap(SkBitmap::kARGB_8888_Config, &bitmap);
     uint8_t rowColor = 0;
     for (int y = 0; y < SLIDE_SIZE; y++) {
         uint32_t* dst = bitmap.getAddr32(0, y);
         for (int x = 0; x < SLIDE_SIZE; x++) {
@@ skipping 86 matching lines @@
         canvas->drawBitmap(make_argb8888_stripes(), 0, slideSize);
         canvas->drawBitmap(make_argb4444_stripes(), slideSize, slideSize);
     }
 
 private:
     typedef GM INHERITED;
 };
 
 DEF_GM( return new BitmapPremulGM; )
 }