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

gm/tilemodes.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"
 #include "SkPath.h"
 #include "SkRegion.h"
 #include "SkShader.h"
 #include "SkUtils.h"
 #include "SkColorPriv.h"
 #include "SkColorFilter.h"
 #include "SkTypeface.h"
 
 // effects
 #include "SkGradientShader.h"
 #include "SkUnitMappers.h"
 #include "SkBlurDrawLooper.h"
 
 static void makebm(SkBitmap* bm, SkBitmap::Config config, int w, int h) {
-    bm->setConfig(config, w, h);
-    bm->allocPixels();
+    bm->allocConfigPixels(config, w, h);
     bm->eraseColor(SK_ColorTRANSPARENT);
 
     SkCanvas    canvas(*bm);
     SkPoint     pts[] = { { 0, 0 }, { SkIntToScalar(w), SkIntToScalar(h)} };
     SkColor     colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE };
     SkScalar    pos[] = { 0, SK_Scalar1/2, SK_Scalar1 };
     SkPaint     paint;
 
     SkUnitMapper*   um = NULL;
 
@@ skipping 227 matching lines @@
 private:
     typedef skiagm::GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 DEF_GM( return new TilingGM(true); )
 DEF_GM( return new TilingGM(false); )
 DEF_GM( return new Tiling2GM(make_bm, "bitmap"); )
 DEF_GM( return new Tiling2GM(make_grad, "gradient"); )