make allocPixels throw on failure

samplecode/SampleUnpremul.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 "Resources.h"
@@ skipping 110 matching lines @@
         canvas->drawText(header.c_str(), header.size(), 0, height, paint);
 
         // Now draw the image itself.
         canvas->translate(height * 2, height * 2);
         if (!fPremul) {
             // A premultiplied bitmap cannot currently be drawn.
             SkAutoLockPixels alp(fBitmap);
             // Copy it to a bitmap which can be drawn, converting
             // to premultiplied:
             SkBitmap bm;
-            if (!bm.allocN32Pixels(fBitmap.width(), fBitmap.height())) {
-                SkString errMsg("allocPixels failed");
-                canvas->drawText(errMsg.c_str(), errMsg.size(), 0, height, paint);
-                return;
-            }
+            bm.allocN32Pixels(fBitmap.width(), fBitmap.height());
             for (int i = 0; i < fBitmap.width(); ++i) {
                 for (int j = 0; j < fBitmap.height(); ++j) {
                     *bm.getAddr32(i, j) = premultiply_unpmcolor(*fBitmap.getAddr32(i, j));
                 }
             }
             canvas->drawBitmap(bm, 0, 0);
         } else {
             canvas->drawBitmap(fBitmap, 0, 0);
         }
     }
@@ skipping 51 matching lines @@
 
     typedef SampleView INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static SkView* MyFactory() {
     return new UnpremulView(GetResourcePath());
 }
 static SkViewRegister reg(MyFactory);