Image Filters: refactor all CPU input processing into a filterInput helper function.

src/effects/SkComposeImageFilter.cpp

Index: src/effects/SkComposeImageFilter.cpp
diff --git a/src/effects/SkComposeImageFilter.cpp b/src/effects/SkComposeImageFilter.cpp
index 2b1606a8a40b0a12570af65416754eb698a0cb5c..6361cdcc6cf81baef4f8b79bfdc7333bde31d19d 100644
--- a/src/effects/SkComposeImageFilter.cpp
+++ b/src/effects/SkComposeImageFilter.cpp
@@ -27,19 +27,16 @@ bool SkComposeImageFilter::onFilterImage(Proxy* proxy,
                                          const Context& ctx,
                                          SkBitmap* result,
                                          SkIPoint* offset) const {
-    SkImageFilter* outer = getInput(0);
-    SkImageFilter* inner = getInput(1);
-
     SkBitmap tmp;
     SkIPoint innerOffset = SkIPoint::Make(0, 0);
     SkIPoint outerOffset = SkIPoint::Make(0, 0);
-    if (!inner->filterImage(proxy, src, ctx, &tmp, &innerOffset))
+    if (!this->filterInput(1, proxy, src, ctx, &tmp, &innerOffset))
         return false;
 
     SkMatrix outerMatrix(ctx.ctm());
     outerMatrix.postTranslate(SkIntToScalar(-innerOffset.x()), SkIntToScalar(-innerOffset.y()));
     Context outerContext(outerMatrix, ctx.clipBounds(), ctx.cache());
-    if (!outer->filterImage(proxy, tmp, outerContext, result, &outerOffset)) {
+    if (!this->filterInput(0, proxy, tmp, outerContext, result, &outerOffset)) {
         return false;
     }