pre-land special methods on device

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2161233002

Review-Url: https://codereview.chromium.org/2161233002
diff --git a/src/pdf/SkPDFDevice.h b/src/pdf/SkPDFDevice.h
index 7c7ddf4..ca78663 100644
--- a/src/pdf/SkPDFDevice.h
+++ b/src/pdf/SkPDFDevice.h
@@ -201,6 +201,11 @@
 
     void drawAnnotation(const SkDraw&, const SkRect&, const char key[], SkData* value) override;
 
+    void drawSpecial(const SkDraw&, SkSpecialImage*, int x, int y, const SkPaint&) override;
+    sk_sp<SkSpecialImage> makeSpecial(const SkBitmap&) override;
+    sk_sp<SkSpecialImage> makeSpecial(const SkImage*) override;
+    sk_sp<SkSpecialImage> snapSpecial() override;
+
 private:
     struct RectWithData {
         SkRect rect;