add pipecanvas

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2201323003

Review-Url: https://codereview.chromium.org/2201323003
diff --git a/dm/DM.cpp b/dm/DM.cpp
index a8fb43b..1598bcd 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -868,6 +868,7 @@
         SINK("f16",  RasterSink, kRGBA_F16_SkColorType, srgbColorSpace->makeLinearGamma());
         SINK("pdf",  PDFSink);
         SINK("skp",  SKPSink);
+        SINK("pipe", PipeSink);
         SINK("svg",  SVGSink);
         SINK("null", NullSink);
         SINK("xps",  XPSSink);
@@ -880,6 +881,7 @@
 static Sink* create_via(const SkString& tag, Sink* wrapped) {
 #define VIA(t, via, ...) if (tag.equals(t)) { return new via(__VA_ARGS__); }
     VIA("lite",      ViaLite,              wrapped);
+    VIA("pipe",      ViaPipe,              wrapped);
     VIA("twice",     ViaTwice,             wrapped);
     VIA("serialize", ViaSerialization,     wrapped);
     VIA("pic",       ViaPicture,           wrapped);