make allocPixels throw on failure

src/effects/SkDisplacementMapEffect.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 "SkDisplacementMapEffect.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ skipping 236 matching lines @@
         return false;
     }
     if (!bounds.intersect(displBounds)) {
         return false;
     }
     SkAutoLockPixels alp_displacement(displ), alp_color(color);
     if (!displ.getPixels() || !color.getPixels()) {
         return false;
     }
 
-    if (!dst->allocPixels(color.info().makeWH(bounds.width(), bounds.height()))) {
+    if (!dst->tryAllocPixels(color.info().makeWH(bounds.width(), bounds.height()))) {
         return false;
     }
 
     SkVector scale = SkVector::Make(fScale, fScale);
     ctx.ctm().mapVectors(&scale, 1);
     SkIRect colorBounds = bounds;
     colorBounds.offset(-colorOffset);
 
     computeDisplacement(fXChannelSelector, fYChannelSelector, scale, dst,
                         &displ, colorOffset - displOffset, &color, colorBounds);
@@ skipping 367 matching lines @@
                                        const GrGLCaps&, GrEffectKeyBuilder* b) {
     const GrDisplacementMapEffect& displacementMap =
         drawEffect.castEffect<GrDisplacementMapEffect>();
 
     uint32_t xKey = displacementMap.xChannelSelector();
     uint32_t yKey = displacementMap.yChannelSelector() << kChannelSelectorKeyBits;
 
     b->add32(xKey | yKey);
 }
 #endif