DM: more invariants

dm/DMSrcSink.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef DMSrcSink_DEFINED
 #define DMSrcSink_DEFINED
 
@@ skipping 311 matching lines @@
 private:
     bool fCache;
 };
 
 class ViaSerialization : public Via {
 public:
     explicit ViaSerialization(Sink* sink) : Via(sink) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 };
 
+class ViaPicture : public Via {
+public:
+    explicit ViaPicture(Sink* sink) : Via(sink) {}
+    Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
+};
+
 class ViaTiles : public Via {
 public:
     ViaTiles(int w, int h, SkBBHFactory*, Sink*);
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 private:
     const int                   fW, fH;
     SkAutoTDelete<SkBBHFactory> fFactory;
 };
 
 class ViaSecondPicture : public Via {
@@ skipping 10 matching lines @@
 
 class ViaTwice : public Via {
 public:
     explicit ViaTwice(Sink* sink) : Via(sink) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 };
 
 }  // namespace DM
 
 #endif//DMSrcSink_DEFINED