make allocPixels throw on failure

src/gpu/GrSurface.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 "GrSurface.h"
 
 #include "SkBitmap.h"
 #include "SkGr.h"
 #include "SkImageEncoder.h"
 #include <stdio.h>
 
 SkImageInfo GrSurface::info() const {
     SkImageInfo info;
     if (!GrPixelConfig2ColorType(this->config(), &info.fColorType)) {
         sk_throw();
     }
     info.fWidth = this->width();
     info.fHeight = this->height();
     info.fAlphaType = kPremul_SkAlphaType;
     return info;
 }
 
 bool GrSurface::savePixels(const char* filename) {
     SkBitmap bm;
-    if (!bm.allocPixels(SkImageInfo::MakeN32Premul(this->width(),
-                                                   this->height()))) {
+    if (!bm.tryAllocPixels(SkImageInfo::MakeN32Premul(this->width(), this->height()))) {
         return false;
     }
 
     bool result = readPixels(0, 0, this->width(), this->height(), kSkia8888_GrPixelConfig,
                              bm.getPixels());
     if (!result) {
         SkDebugf("------ failed to read pixels for %s\n", filename);
         return false;
     }
 
     // remove any previous version of this file
     remove(filename);
 
     if (!SkImageEncoder::EncodeFile(filename, bm, SkImageEncoder::kPNG_Type, 100)) {
         SkDebugf("------ failed to encode %s\n", filename);
         remove(filename);   // remove any partial file
         return false;
     }
 
     return true;
 }