Created methods to surface zone memory information for each isolate and thread in JSON.

runtime/vm/zone.cc

Index: runtime/vm/zone.cc
diff --git a/runtime/vm/zone.cc b/runtime/vm/zone.cc
index 45314dcfe32d7887d91f82978eaecdfa50cdbce5..10dab8ef58ac1e563d0de429f6cd4b6b603e9bd2 100644
--- a/runtime/vm/zone.cc
+++ b/runtime/vm/zone.cc
@@ -260,6 +260,17 @@ char* Zone::VPrint(const char* format, va_list args) {
 }
 
 
+#if defined(DEBUG)

[zra, 2016/12/08 18:54:13]

ditto

[bkonyi, 2016/12/08 20:58:32]

Done.

+void Zone::PrintJSON(JSONStream* stream, bool ref) const {
+  JSONObject jsobj(stream);
+  intptr_t capacity = SizeInBytes();
+  intptr_t used_size = UsedSizeInBytes();
+  jsobj.AddProperty("type", "_Zone");
+  jsobj.AddProperty("capacity", capacity);
+  jsobj.AddProperty("used", used_size);
+}
+#endif
+

[zra, 2016/12/08 18:54:14]

two newlines between functions.

[bkonyi, 2016/12/08 20:58:32]

Done.

 StackZone::StackZone(Thread* thread) : StackResource(thread), zone_() {
   if (FLAG_trace_zones) {
     OS::PrintErr("*** Starting a new Stack zone 0x%" Px "(0x%" Px ")\n",