DM: fix `--config $VIA-pdf` to not crash

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 271 matching lines @@
     int enclave() const override { return kAnyThread_Enclave; }
     const char* fileExtension() const override { return "svg"; }
     SinkFlags flags() const override { return SinkFlags{ SinkFlags::kVector, SinkFlags::kDirect }; }
 };
 
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 class Via : public Sink {
 public:
-    explicit Via(Sink* sink) : fSink(sink) {}
+    explicit Via(Name name, Sink* sink) : fName(name), fSink(sink) {}
     const char* fileExtension() const override { return fSink->fileExtension(); }
     int               enclave() const override { return fSink->enclave(); }
+    Name decorateName(const Src& src) const {
+        return SkStringPrintf("%s-%s", src.name().c_str(), fName.c_str());
+    }
     SinkFlags flags() const override {
         SinkFlags flags = fSink->flags();
         flags.approach = SinkFlags::kIndirect;
         return flags;
     }
 protected:
+    Name fName;
     SkAutoTDelete<Sink> fSink;
 };
 
 class ViaMatrix : public Via {
 public:
-    ViaMatrix(SkMatrix, Sink*);
+    ViaMatrix(Name, SkMatrix, Sink*);
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 private:
     const SkMatrix fMatrix;
 };
 
 class ViaUpright : public Via {
 public:
-    ViaUpright(SkMatrix, Sink*);
+    ViaUpright(Name, SkMatrix, Sink*);
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 private:
     const SkMatrix fMatrix;
 };
 
 class ViaPipe : public Via {
 public:
-    explicit ViaPipe(Sink* sink) : Via(sink) {}
+    explicit ViaPipe(Name name, Sink* sink) : Via(name, sink) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 };
 
 class ViaRemote : public Via {
 public:
-    ViaRemote(bool cache, Sink* sink) : Via(sink), fCache(cache) {}
+    ViaRemote(Name name, bool cache, Sink* sink) : Via(name, sink), fCache(cache) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 private:
     bool fCache;
 };
 
 class ViaSerialization : public Via {
 public:
-    explicit ViaSerialization(Sink* sink) : Via(sink) {}
+    explicit ViaSerialization(Name name, Sink* sink) : Via(name, sink) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 };
 
 class ViaTiles : public Via {
 public:
-    ViaTiles(int w, int h, SkBBHFactory*, Sink*);
+    ViaTiles(Name, 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 {
 public:
-    explicit ViaSecondPicture(Sink* sink) : Via(sink) {}
+    explicit ViaSecondPicture(Name name, Sink* sink) : Via(name, sink) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 };
 
 class ViaSingletonPictures : public Via {
 public:
-    explicit ViaSingletonPictures(Sink* sink) : Via(sink) {}
+    explicit ViaSingletonPictures(Name name, Sink* sink) : Via(name, sink) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 };
 
 class ViaTwice : public Via {
 public:
-    explicit ViaTwice(Sink* sink) : Via(sink) {}
+    explicit ViaTwice(Name name, Sink* sink) : Via(name, sink) {}
     Error draw(const Src&, SkBitmap*, SkWStream*, SkString*) const override;
 };
 
 }  // namespace DM
 
 #endif//DMSrcSink_DEFINED