Mark existing image filter entry points that will be going away with Deprecated

src/effects/SkDropShadowImageFilter.cpp

Index: src/effects/SkDropShadowImageFilter.cpp
diff --git a/src/effects/SkDropShadowImageFilter.cpp b/src/effects/SkDropShadowImageFilter.cpp
index 5f8736f3a597049870962a1085b97325f731f619..e2e72c1097478c39a691cd63d1b2159152340a2a 100644
--- a/src/effects/SkDropShadowImageFilter.cpp
+++ b/src/effects/SkDropShadowImageFilter.cpp
@@ -53,13 +53,12 @@ void SkDropShadowImageFilter::flatten(SkWriteBuffer& buffer) const {
     buffer.writeInt(static_cast<int>(fShadowMode));
 }
 
-bool SkDropShadowImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source,
-                                            const Context& ctx,
-                                            SkBitmap* result, SkIPoint* offset) const
-{
+bool SkDropShadowImageFilter::onFilterImageDeprecated(Proxy* proxy, const SkBitmap& source,
+                                                      const Context& ctx,
+                                                      SkBitmap* result, SkIPoint* offset) const {
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
-    if (!this->filterInput(0, proxy, source, ctx, &src, &srcOffset))
+    if (!this->filterInputDeprecated(0, proxy, source, ctx, &src, &srcOffset))
         return false;
 
     SkIRect srcBounds = src.bounds();