Track async causal stack traces

runtime/vm/thread.cc

Index: runtime/vm/thread.cc
diff --git a/runtime/vm/thread.cc b/runtime/vm/thread.cc
index 16091844b0ee92302c0885f62fb57482e5b61685..dc54d6a01a2f1247565635c47a29582929588ca4 100644
--- a/runtime/vm/thread.cc
+++ b/runtime/vm/thread.cc
@@ -70,6 +70,7 @@ Thread::Thread(Isolate* isolate)
       store_buffer_block_(NULL),
       vm_tag_(0),
       task_kind_(kUnknownTask),
+      async_stack_trace_(StackTrace::null()),
       dart_stream_(NULL),
       os_thread_(NULL),
       thread_lock_(new Monitor()),
@@ -303,6 +304,27 @@ const char* Thread::TaskKindToCString(TaskKind kind) {
 }
 
 
+RawStackTrace* Thread::async_stack_trace() const {
+  return async_stack_trace_;
+}
+
+
+void Thread::set_async_stack_trace(const StackTrace& stack_trace) {
+  ASSERT(!stack_trace.IsNull());
+  async_stack_trace_ = stack_trace.raw();
+}
+
+
+void Thread::set_raw_async_stack_trace(RawStackTrace* raw_stack_trace) {
+  async_stack_trace_ = raw_stack_trace;
+}
+
+
+void Thread::clear_async_stack_trace() {
+  async_stack_trace_ = StackTrace::null();
+}
+
+
 bool Thread::EnterIsolate(Isolate* isolate) {
   const bool kIsMutatorThread = true;
   Thread* thread = isolate->ScheduleThread(kIsMutatorThread);
@@ -681,6 +703,7 @@ void Thread::VisitObjectPointers(ObjectPointerVisitor* visitor,
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&active_exception_));
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&active_stacktrace_));
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&sticky_error_));
+  visitor->VisitPointer(reinterpret_cast<RawObject**>(&async_stack_trace_));
 
   // Visit the api local scope as it has all the api local handles.
   ApiLocalScope* scope = api_top_scope_;