make allocPixels throw on failure

src/effects/SkMatrixConvolutionImageFilter.cpp

Index: src/effects/SkMatrixConvolutionImageFilter.cpp
diff --git a/src/effects/SkMatrixConvolutionImageFilter.cpp b/src/effects/SkMatrixConvolutionImageFilter.cpp
index aa8b8049c9a94e95d1c64224f859ec5ccadf98ec..c8959eecfbe01dbab865cc8e25e248fa3ddcc6e7 100644
--- a/src/effects/SkMatrixConvolutionImageFilter.cpp
+++ b/src/effects/SkMatrixConvolutionImageFilter.cpp
@@ -265,7 +265,7 @@ static SkBitmap unpremultiplyBitmap(const SkBitmap& src)
         return SkBitmap();
     }
     SkBitmap result;
-    if (!result.allocPixels(src.info())) {
+    if (!result.tryAllocPixels(src.info())) {
         return SkBitmap();
     }
     for (int y = 0; y < src.height(); ++y) {
@@ -307,7 +307,7 @@ bool SkMatrixConvolutionImageFilter::onFilterImage(Proxy* proxy,
         return false;
     }
 
-    if (!result->allocPixels(src.info().makeWH(bounds.width(), bounds.height()))) {
+    if (!result->tryAllocPixels(src.info().makeWH(bounds.width(), bounds.height()))) {
         return false;
     }