Show pid on Observatory VM page

runtime/vm/service.cc

Index: runtime/vm/service.cc
diff --git a/runtime/vm/service.cc b/runtime/vm/service.cc
index bd24d2a39a71a73e14565a2e76dcc94e8c36e51d..aab952838b2961731a26f788434f1f7d1c2a5880 100644
--- a/runtime/vm/service.cc
+++ b/runtime/vm/service.cc
@@ -1939,6 +1939,10 @@ static bool HandleVM(JSONStream* js) {
   jsobj.AddProperty("targetCPU", CPU::Id());
   jsobj.AddProperty("hostCPU", HostCPUFeatures::hardware());
   jsobj.AddProperty("version", Version::String());
+  // Send pid as a string because it allows us to avoid any issues with
+  // pids > 53-bits (when consumed by JavaScript).
+  // TODO(johnmccutchan): Codify how integers are sent across the service.
+  jsobj.AddPropertyF("pid", "%" Pd "", OS::ProcessId());
   jsobj.AddProperty("assertsEnabled", FLAG_enable_asserts);
   jsobj.AddProperty("typeChecksEnabled", FLAG_enable_type_checks);
   int64_t start_time_micros = Dart::vm_isolate()->start_time();