SkDocument::setDCTEncoder() for old versions of webkit

src/pdf/SkPDFCanon.h

Index: src/pdf/SkPDFCanon.h
diff --git a/src/pdf/SkPDFCanon.h b/src/pdf/SkPDFCanon.h
index 3d2ba6a77d1b4b2ea36023814c11080553e33e65..63f11d5670e2148e2d777a702417764bb73242f0 100644
--- a/src/pdf/SkPDFCanon.h
+++ b/src/pdf/SkPDFCanon.h
@@ -49,6 +49,7 @@ private:
  */
 class SkPDFCanon : SkNoncopyable {
 public:
+    SkPDFCanon() : fEncoder(nullptr) {}
     ~SkPDFCanon() { this->reset(); }
 
     // reset to original setting, unrefs all objects.
@@ -80,6 +81,8 @@ public:
 
     SkTHashMap<uint32_t, bool> fCanEmbedTypeface;
 
+    SkData* (*fEncoder)(const SkPixmap&);
+
 private:
     struct FontRec {
         SkPDFFont* fFont;