adding preabandon flag to DM

BUG=skia:

Review URL: https://codereview.chromium.org/929243004
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index d7c874c..491f598 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -965,6 +965,9 @@
         texDesc.fConfig = kAlpha_8_GrPixelConfig;
 
         blurNinePatchTexture = context->createTexture(texDesc, true, blurred_mask.fImage, 0);
+        if (!blurNinePatchTexture) {
+            return NULL;
+        }
         context->addResourceToCache(key, blurNinePatchTexture);
 
         SkMask::FreeImage(blurred_mask.fImage);