make allocPixels throw on failure

src/images/SkImageDecoder_libjpeg.cpp

Index: src/images/SkImageDecoder_libjpeg.cpp
diff --git a/src/images/SkImageDecoder_libjpeg.cpp b/src/images/SkImageDecoder_libjpeg.cpp
index 9b937162b3e153c33dac0d26423bcd7ad1ae4ce3..99401e6b627cdc9fd023b304a6c40789c3fbec3d 100644
--- a/src/images/SkImageDecoder_libjpeg.cpp
+++ b/src/images/SkImageDecoder_libjpeg.cpp
@@ -852,7 +852,7 @@ bool SkJPEGImageDecoder::onDecodeSubset(SkBitmap* bm, const SkIRect& region) {
             return return_false(*cinfo, bitmap, "allocPixelRef");
         }
     } else {
-        if (!bitmap.allocPixels()) {
+        if (!bitmap.tryAllocPixels()) {
             return return_false(*cinfo, bitmap, "allocPixels");
         }
     }