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

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 2503dc35cec207602df6e50d9f66a518d108f2d1..a3f1cf6cba963430253aa3549dc6b99342e21a55 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -992,19 +992,21 @@ Error RasterSink::draw(const Src& src, SkBitmap* dst, SkWStream*, SkString*) con
 // passing the Sink draw() arguments, a size, and a function draws into an SkCanvas.
 // Several examples below.
 
-static Error draw_to_canvas(Sink* sink, SkBitmap* bitmap, SkWStream* stream, SkString* log,
+static Error draw_to_canvas(Name name, Sink* sink, SkBitmap* bitmap, SkWStream* stream, SkString* log,
                             SkISize size, std::function<Error(SkCanvas*)> draw) {
     class ProxySrc : public Src {
     public:
-        ProxySrc(SkISize size, std::function<Error(SkCanvas*)> draw) : fSize(size), fDraw(draw) {}
+        ProxySrc(SkISize size, Name name, std::function<Error(SkCanvas*)> draw)
+            : fSize(size), fName(name), fDraw(draw) {}
         Error   draw(SkCanvas* canvas) const override { return fDraw(canvas); }
-        Name                    name() const override { sk_throw(); return ""; } // Won't be called.
+        Name                    name() const override { return fName; }
         SkISize                 size() const override { return fSize; }
     private:
         SkISize                         fSize;
+        Name fName;
         std::function<Error(SkCanvas*)> fDraw;
     };
-    return sink->draw(ProxySrc(size, draw), bitmap, stream, log);
+    return sink->draw(ProxySrc(size, name, draw), bitmap, stream, log);
 }
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
@@ -1021,7 +1023,8 @@ ViaMatrix::ViaMatrix(SkMatrix matrix, Sink* sink) : Via(sink), fMatrix(matrix) {
 Error ViaMatrix::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkString* log) const {
     SkMatrix matrix = fMatrix;
     SkISize size = auto_compute_translate(&matrix, src.size().width(), src.size().height());
-    return draw_to_canvas(fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) {
+    Name name = SkStringPrintf("%s [via matrix]", src.name().c_str());

[mtklein, 2015/12/10 19:27:57]

Some ideas:
   - thread the names from DM.cpp so we can keep them exactly in sync with the
name used to construct the Via, probably working this into the VIA macro?
   - plop a method on the Via base class to do the bulk of this logic, e.g.
draw_to_canvas(this->decorateName(src), ...) ?
   - consider mirroring the format we use to construct the Vias more closely, so
it's clearer how to reproduce, e.g. "%s-%s", src.name(), via.name(), so that
instead of
  "all_bitmap_configs [via serialization] [via matrix]"
we get
  "all_bitmap_configs-serialize-matrix"

[hal.canary, 2015/12/10 20:08:47]

done
done
done

+    return draw_to_canvas(name, fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) {
         canvas->concat(matrix);
         return src.draw(canvas);
     });
@@ -1066,7 +1069,8 @@ Error ViaUpright::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkSt
 
 Error ViaPipe::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkString* log) const {
     auto size = src.size();
-    return draw_to_canvas(fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) {
+    Name name = SkStringPrintf("%s [via pipe]", src.name().c_str());
+    return draw_to_canvas(name, fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) {
         PipeController controller(canvas, &SkImageDecoder::DecodeMemory);
         SkGPipeWriter pipe;
         const uint32_t kFlags = 0;
@@ -1075,7 +1079,8 @@ Error ViaPipe::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkStrin
 }
 
 Error ViaRemote::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkString* log) const {
-    return draw_to_canvas(fSink, bitmap, stream, log, src.size(), [&](SkCanvas* target) {
+    Name name = SkStringPrintf("%s [via remote]", src.name().c_str());
+    return draw_to_canvas(name, fSink, bitmap, stream, log, src.size(), [&](SkCanvas* target) {
         SkAutoTDelete<SkRemote::Encoder> decoder(SkRemote::NewDecoder(target));
         SkAutoTDelete<SkRemote::Encoder>   cache(fCache ? SkRemote::NewCachingEncoder(decoder)
                                                         : nullptr);
@@ -1103,8 +1108,9 @@ Error ViaSerialization::draw(
     pic->serialize(&wStream);
     SkAutoTDelete<SkStream> rStream(wStream.detachAsStream());
     SkAutoTUnref<SkPicture> deserialized(SkPicture::CreateFromStream(rStream, &lazy_decode_bitmap));
+    Name name = SkStringPrintf("%s [via serialization]", src.name().c_str());
 
-    return draw_to_canvas(fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) {
+    return draw_to_canvas(name, fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) {
         canvas->drawPicture(deserialized);
         return "";
     });
@@ -1128,8 +1134,9 @@ Error ViaTiles::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkStri
         return err;
     }
     SkAutoTUnref<SkPicture> pic(recorder.endRecordingAsPicture());
+    Name name = SkStringPrintf("%s [via tiles]", src.name().c_str());
 
-    return draw_to_canvas(fSink, bitmap, stream, log, src.size(), [&](SkCanvas* canvas) {
+    return draw_to_canvas(name, fSink, bitmap, stream, log, src.size(), [&](SkCanvas* canvas) {
         const int xTiles = (size.width()  + fW - 1) / fW,
                   yTiles = (size.height() + fH - 1) / fH;
         SkMultiPictureDraw mpd(xTiles*yTiles);
@@ -1171,7 +1178,8 @@ Error ViaTiles::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkStri
 Error ViaSecondPicture::draw(
         const Src& src, SkBitmap* bitmap, SkWStream* stream, SkString* log) const {
     auto size = src.size();
-    return draw_to_canvas(fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) -> Error {
+    Name name = SkStringPrintf("%s [via second picture]", src.name().c_str());
+    return draw_to_canvas(name, fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) -> Error {
         SkPictureRecorder recorder;
         SkAutoTUnref<SkPicture> pic;
         for (int i = 0; i < 2; i++) {
@@ -1191,7 +1199,8 @@ Error ViaSecondPicture::draw(
 
 // Draw the Src twice.  This can help exercise caching.
 Error ViaTwice::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkString* log) const {
-    return draw_to_canvas(fSink, bitmap, stream, log, src.size(), [&](SkCanvas* canvas) -> Error {
+    Name name = SkStringPrintf("%s [via twice]", src.name().c_str());
+    return draw_to_canvas(name, fSink, bitmap, stream, log, src.size(), [&](SkCanvas* canvas) -> Error {
         for (int i = 0; i < 2; i++) {
             SkAutoCanvasRestore acr(canvas, true/*save now*/);
             canvas->clear(SK_ColorTRANSPARENT);
@@ -1243,7 +1252,8 @@ struct DrawsAsSingletonPictures {
 Error ViaSingletonPictures::draw(
         const Src& src, SkBitmap* bitmap, SkWStream* stream, SkString* log) const {
     auto size = src.size();
-    return draw_to_canvas(fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) -> Error {
+    Name name = SkStringPrintf("%s [via singleton_pictures]", src.name().c_str());
+    return draw_to_canvas(name, fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) -> Error {
         // Use low-level (Skia-private) recording APIs so we can read the SkRecord.
         SkRecord skr;
         SkRecorder recorder(&skr, size.width(), size.height());