DM: allow vias to work with PDF backend

dm/DMSrcSink.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "DMSrcSink.h"
 #include "SkAndroidCodec.h"
 #include "SkCodec.h"
@@ skipping 1144 matching lines @@
 // passing the Sink draw() arguments, a size, and a function draws into an SkCanvas.
 // Several examples below.
 
 template <typename Fn>
 static Error draw_to_canvas(Sink* sink, SkBitmap* bitmap, SkWStream* stream, SkString* log,
                             SkISize size, const Fn& draw) {
     class ProxySrc : public Src {
     public:
         ProxySrc(SkISize size, const Fn& draw) : fSize(size), fDraw(draw) {}
         Error   draw(SkCanvas* canvas) const override { return fDraw(canvas); }
-        Name                    name() const override { sk_throw(); return ""; } // Won't be called.
-        SkISize                 size() const override { return fSize; }
+        Name    name() const override { return "ProxySrc"; }
+        SkISize size() const override { return fSize; }
     private:
         SkISize   fSize;
         const Fn& fDraw;
     };
     return sink->draw(ProxySrc(size, draw), bitmap, stream, log);
 }
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 DEFINE_bool(check, true, "If true, have most Via- modes fail if they affect the output.");
 
 // Is *bitmap identical to what you get drawing src into sink?
 static Error check_against_reference(const SkBitmap* bitmap, const Src& src, Sink* sink) {
     // We can only check raster outputs.
     // (Non-raster outputs like .pdf, .skp, .svg may differ but still draw identically.)
     if (FLAGS_check && bitmap) {
         SkBitmap reference;
         SkString log;
-        Error err = sink->draw(src, &reference, nullptr, &log);
+        SkDynamicMemoryWStream wStream;
+        Error err = sink->draw(src, &reference, &wStream, &log);
         // If we can draw into this Sink via some pipeline, we should be able to draw directly.
         SkASSERT(err.isEmpty());
         if (!err.isEmpty()) {
             return err;
         }
         // The dimensions are a property of the Src only, and so should be identical.
         SkASSERT(reference.getSize() == bitmap->getSize());
         if (reference.getSize() != bitmap->getSize()) {
             return "Dimensions don't match reference";
         }
@@ skipping 310 matching lines @@
             skr.visit(i, drawsAsSingletonPictures);
         }
         sk_sp<SkPicture> macroPic(macroRec.finishRecordingAsPicture());
 
         canvas->drawPicture(macroPic);
         return check_against_reference(bitmap, src, fSink);
     });
 }
 
 }  // namespace DM