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

gm/bitmapscroll.cpp

 
 /*
  * Copyright 2011 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"
 
 namespace skiagm {
 
 /** Create a bitmap image suitable for testing SkBitmap::scrollRect().
  *
  *  @param quarterWidth bitmap will be 4x this many pixels wide
  *  @param quarterHeight bitmap will be 4x this many pixels tall
  *  @param bitmap the bitmap data is written into this object
  */
 static void make_bitmap(int quarterWidth, int quarterHeight, SkBitmap *bitmap) {
     SkPaint pRed, pWhite, pGreen, pBlue, pLine, pAlphaGray;
     pRed.setColor(0xFFFF9999);
     pWhite.setColor(0xFFFFFFFF);
     pGreen.setColor(0xFF99FF99);
     pBlue.setColor(0xFF9999FF);
     pLine.setColor(0xFF000000);
     pLine.setStyle(SkPaint::kStroke_Style);
     pAlphaGray.setColor(0x66888888);
 
     // Prepare bitmap, and a canvas that draws into it.
-    bitmap->reset();
-    bitmap->setConfig(SkBitmap::kARGB_8888_Config,
-                      quarterWidth*4, quarterHeight*4);
-    bitmap->allocPixels();
+    bitmap->allocN32Pixels(quarterWidth*4, quarterHeight*4);
     SkCanvas canvas(*bitmap);
 
     SkScalar w = SkIntToScalar(quarterWidth);
     SkScalar h = SkIntToScalar(quarterHeight);
     canvas.drawRectCoords(  0,   0, w*2, h*2, pRed);
     canvas.drawRectCoords(w*2,   0, w*4, h*2, pGreen);
     canvas.drawRectCoords(  0, h*2, w*2, h*4, pBlue);
     canvas.drawRectCoords(w*2, h*2, w*4, h*4, pWhite);
     canvas.drawRectCoords(w, h, w*3, h*3, pAlphaGray);
     canvas.drawLine(w*2,   0, w*2, h*4, pLine);
@@ skipping 105 matching lines @@
     static const int quarterHeight = 14;
     SkBitmap origBitmap;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new BitmapScrollGM; }
 static GMRegistry reg(MyFactory);
 
 }