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

gm/bigmatrix.cpp

 
 /*
  * Copyright 2012 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 "SkColorPriv.h"
@@ skipping 41 matching lines @@
         path.addCircle(pt.fX, pt.fY, small);
         canvas->drawPath(path, paint);
 
         pt.set(30 * SK_Scalar1, 10 * SK_Scalar1);
         m.mapPoints(&pt, 1);
         SkRect rect = {pt.fX - small, pt.fY - small,
                        pt.fX + small, pt.fY + small};
         canvas->drawRect(rect, paint);
 
         SkBitmap bmp;
-        bmp.setConfig(SkBitmap::kARGB_8888_Config, 2, 2);
-        bmp.allocPixels();
-        bmp.lockPixels();
+        bmp.allocN32Pixels(2, 2);
         uint32_t* pixels = reinterpret_cast<uint32_t*>(bmp.getPixels());
         pixels[0] = SkPackARGB32(0xFF, 0xFF, 0x00, 0x00);
         pixels[1] = SkPackARGB32(0xFF, 0x00, 0xFF, 0x00);
         pixels[2] = SkPackARGB32(0x80, 0x00, 0x00, 0x00);
         pixels[3] = SkPackARGB32(0xFF, 0x00, 0x00, 0xFF);
-        bmp.unlockPixels();
         pt.set(30 * SK_Scalar1, 30 * SK_Scalar1);
         m.mapPoints(&pt, 1);
         SkShader* shader = SkShader::CreateBitmapShader(
                                             bmp,
                                             SkShader::kRepeat_TileMode,
                                             SkShader::kRepeat_TileMode);
         SkMatrix s;
         s.reset();
         s.setScale(SK_Scalar1 / 1000, SK_Scalar1 / 1000);
         shader->setLocalMatrix(s);
         paint.setShader(shader)->unref();
         paint.setAntiAlias(false);
         paint.setFilterLevel(SkPaint::kLow_FilterLevel);
         rect.setLTRB(pt.fX - small, pt.fY - small,
                      pt.fX + small, pt.fY + small);
         canvas->drawRect(rect, paint);
     }
 
 private:
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new BigMatrixGM; }
 static GMRegistry reg(MyFactory);
 
 }