check for inputs before reporting asColorFilter

src/effects/SkColorFilterImageFilter.cpp

Index: src/effects/SkColorFilterImageFilter.cpp
diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index fdf6de7b76daf755f2fea5d49c87a753374e3cb7..908f814b945e2c35a8ff43f6bb1ce2f9c328a6ce 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -21,10 +21,12 @@ SkColorFilterImageFilter* SkColorFilterImageFilter::Create(SkColorFilter* cf,
         return NULL;
     }
 
-    SkColorFilter* inputColorFilter;
-    if (input && input->asColorFilter(&inputColorFilter)) {
-        SkAutoUnref autoUnref(inputColorFilter);
-        SkAutoTUnref<SkColorFilter> newCF(cf->newComposed(inputColorFilter));
+    SkColorFilter* inputCF;
+    if (input && input->asColorFilter(&inputCF)) {
+        // This is an optimization, as it collapses the hierarchy by just combining the two
+        // colorfilters into a single one, which the new imagefilter will wrap.
+        SkAutoUnref autoUnref(inputCF);
+        SkAutoTUnref<SkColorFilter> newCF(SkColorFilter::CreateComposeFilter(cf, inputCF));
         if (newCF) {
             return SkNEW_ARGS(SkColorFilterImageFilter, (newCF, input->getInput(0), cropRect, 0));
         }
@@ -86,10 +88,13 @@ bool SkColorFilterImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& sourc
 }
 
 bool SkColorFilterImageFilter::asColorFilter(SkColorFilter** filter) const {
-    if (!cropRectIsSet()) {
+    if (!this->cropRectIsSet()) {
+        SkASSERT(1 == this->countInputs());
+        // Since our factory has already performed the collapse optimization, we can assert that
+        // if we have an input, it is *not* also a colorfilter.

[Stephen White, 2015/03/05 18:52:18]

Since we're now limiting the amount of collapsing we do, I think this may no
longer be true.

I suspect this will assert with >4 color filters composed.

+        SkASSERT(!this->getInput(0) || !this->getInput(0)->asColorFilter(NULL));
         if (filter) {
-            *filter = fColorFilter;
-            fColorFilter->ref();
+            *filter = SkRef(fColorFilter);
         }
         return true;
     }