notice null colorfilter in legacy unflattening

src/effects/SkColorFilterImageFilter.cpp

Index: src/effects/SkColorFilterImageFilter.cpp
diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index 806dd5dd010b7758b49a108d87185af77066adff..012f1329a44c552d0f33529ba63d9739ecc5b9e5 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -85,9 +85,17 @@ SkColorFilterImageFilter::SkColorFilterImageFilter(SkColorFilter* cf,
 }
 
 #ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
-SkColorFilterImageFilter::SkColorFilterImageFilter(SkReadBuffer& buffer)
-  : INHERITED(1, buffer) {
+SkColorFilterImageFilter::SkColorFilterImageFilter(SkReadBuffer& buffer) : INHERITED(1, buffer) {
     fColorFilter = buffer.readColorFilter();
+    // we aren't prepared for this to be NULL, and it can't ever be when we're NOT supporting
+    // SK_SUPPORT_LEGACY_DEEPFLATTENING, as we always go through a factory which can detect
+    // NULL. However, since here we're in the legacy code, we assign a dummy filter so we
+    // don't crash with a null-ptr.
+    if (NULL == fColorFilter) {
+        // colormatrix identity is effectively a no-op
+        fColorFilter = SkColorMatrixFilter::Create(SkColorMatrix());
+        SkASSERT(fColorFilter);
+    }
 }
 #endif