make allocPixels throw on failure

src/gpu/GrSWMaskHelper.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 "GrSWMaskHelper.h"
 
 #include "GrDrawState.h"
@@ skipping 187 matching lines @@
             fCompressedBuffer.reset(cmpSz);
             fCompressionMode = kBlitter_CompressionMode;
         }
     } 
 
     // If we don't have a custom blitter, then we either need a bitmap to compress
     // from or a bitmap that we're going to use as a texture. In any case, we should
     // allocate the pixels for a bitmap
     const SkImageInfo bmImageInfo = SkImageInfo::MakeA8(cmpWidth, cmpHeight);
     if (kBlitter_CompressionMode != fCompressionMode) {
-        if (!fBM.allocPixels(bmImageInfo)) {
+        if (!fBM.tryAllocPixels(bmImageInfo)) {
             return false;
         }
 
         sk_bzero(fBM.getPixels(), fBM.getSafeSize());
     } else {
         // Otherwise, we just need to remember how big the buffer is...
         fBM.setInfo(bmImageInfo);
     }
 
     sk_bzero(&fDraw, sizeof(fDraw));
@@ skipping 143 matching lines @@
     maskMatrix.preConcat(drawState->getViewMatrix());
 
     drawState->addCoverageEffect(
                          GrSimpleTextureEffect::Create(texture,
                                                        maskMatrix,
                                                        GrTextureParams::kNone_FilterMode,
                                                        kPosition_GrCoordSet))->unref();
 
     target->drawSimpleRect(dstRect);
 }