SkJson

For now this is only wired to a bench and a couple of tests.

Local numbers, for a ~500KB BM "compressed" json:

    micros   	bench
   2456.54  	json_rapidjson	nonrendering
   1192.38  	json_skjson	nonrendering


Change-Id: I7b3514f84c7c525d1787722c43ad6095e3692563
Reviewed-on: https://skia-review.googlesource.com/127622
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/BUILD.gn b/BUILD.gn
index 85d6694..2a832a5 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1391,6 +1391,7 @@
     ]
     public_deps = [
       ":gpu_tool_utils",  # Test.h #includes headers from this target.
+      "modules/skjson:tests",
     ]
   }
 
@@ -1405,6 +1406,9 @@
       ":skia",
       ":tool_utils",
     ]
+    public_deps = [
+      "modules/skjson:bench",
+    ]
   }
 
   test_lib("experimental_svg_model") {
@@ -1745,6 +1749,7 @@
       ":flags",
       ":gpu_tool_utils",
       ":skia",
+      "modules/skjson:fuzz",
       "modules/skottie:fuzz",
       "//third_party/jsoncpp",
       "//third_party/libpng",