Fix bug in erosion filtering

https://codereview.chromium.org/50813002/



git-svn-id: http://skia.googlecode.com/svn/trunk@11996 2bbb7eff-a529-9590-31e7-b0007b416f81

expectations/gm/ignored-tests.txt

@@ -39,3 +39,7 @@ pdf-poppler
 
 # Added by bsalomon in https://codereview.chromium.org/31033002
 verylargebitmap
+
+# Add by robertphillips in https://codereview.chromium.org/50813002/
+morphology
+

src/effects/SkMorphologyImageFilter.cpp

@@ -507,7 +507,9 @@ bool apply_morphology(const SkBitmap& input,
                               morphType, Gr1DKernelEffect::kX_Direction);
         SkIRect clearRect = SkIRect::MakeXYWH(dstRect.fLeft, dstRect.fBottom,
                                               dstRect.width(), radius.fHeight);
-        context->clear(&clearRect, 0x0);
+        context->clear(&clearRect, GrMorphologyEffect::kErode_MorphologyType == morphType ? 
+                                   SK_ColorWHITE : 
+                                   SK_ColorTRANSPARENT);
         src.reset(ast.detach());
         srcRect = dstRect;
     }