make allocPixels throw on failure

src/core/SkBitmapDevice.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 "SkBitmapDevice.h"
 #include "SkConfig8888.h"
 #include "SkDraw.h"
@@ skipping 64 matching lines @@
         return NULL;
     }
 
     SkBitmap bitmap;
 
     if (kUnknown_SkColorType == info.colorType()) {
         if (!bitmap.setInfo(info)) {
             return NULL;
         }
     } else {
-        if (!bitmap.allocPixels(info)) {
+        if (!bitmap.tryAllocPixels(info)) {
             return NULL;
         }
         if (!bitmap.info().isOpaque()) {
             bitmap.eraseColor(SK_ColorTRANSPARENT);
         }
     }
 
     if (props) {
         return SkNEW_ARGS(SkBitmapDevice, (bitmap, *props));
     } else {
@@ skipping 292 matching lines @@
         paint.getStyle() != SkPaint::kFill_Style ||
         !SkXfermode::IsMode(paint.getXfermode(), SkXfermode::kSrcOver_Mode)) {
         // turn off lcd
         flags->fFlags = paint.getFlags() & ~SkPaint::kLCDRenderText_Flag;
         flags->fHinting = paint.getHinting();
         return true;
     }
     // we're cool with the paint as is
     return false;
 }