[Scheduling APIs] Add support for async callstacks to postTask

This CL adds the necessary wiring to make devtools aware of postTask to
show async callstacks, similar to setTimeout and requestIdleCallback.

Bug: 979017
Change-Id: I960b13d1c13f171dbc033b8e79bff3768e65c347
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2025870Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Scott Haseley <shaseley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736504}

third_party/blink/renderer/modules/scheduler/dom_task.cc

@@ -10,6 +10,7 @@
 #include "third_party/blink/renderer/bindings/core/v8/script_value.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_function.h"
 #include "third_party/blink/renderer/core/dom/dom_exception.h"
+#include "third_party/blink/renderer/core/probe/core_probes.h"
 #include "third_party/blink/renderer/modules/scheduler/dom_scheduler.h"
 #include "third_party/blink/renderer/modules/scheduler/dom_task_signal.h"
 #include "third_party/blink/renderer/platform/bindings/script_state.h"
@@ -41,6 +42,12 @@ DOMTask::DOMTask(DOMScheduler* scheduler,
   task_handle_ = PostDelayedCancellableTask(
       *task_runner, FROM_HERE,
       WTF::Bind(&DOMTask::Invoke, WrapPersistent(this)), delay);
+
+  ScriptState* script_state =
+      callback_->CallbackRelevantScriptStateOrReportError("DOMTask", "Create");
+  DCHECK(script_state && script_state->ContextIsValid());
+  probe::AsyncTaskScheduled(ExecutionContext::From(script_state), "postTask",
+                            &async_task_id_);
 }
 
 void DOMTask::Trace(Visitor* visitor) {
@@ -69,6 +76,11 @@ void DOMTask::InvokeInternal(ScriptState* script_state) {
   v8::TryCatch try_catch(script_state->GetIsolate());
   try_catch.SetVerbose(true);
 
+  ExecutionContext* context = ExecutionContext::From(script_state);
+  DCHECK(context);
+  probe::AsyncTask async_task(context, &async_task_id_);
+  probe::UserCallback probe(context, "postTask", AtomicString(), true);
+
   ScriptValue result;
   if (callback_->Invoke(nullptr, arguments_).To(&result))
     resolver_->Resolve(result.V8Value());
@@ -77,9 +89,20 @@ void DOMTask::InvokeInternal(ScriptState* script_state) {
 }
 
 void DOMTask::Abort() {
+  // If the task has already finished running, the promise is either resolved or
+  // rejected, in which case abort will no longer have any effect.
+  if (!callback_)
+    return;
+
   task_handle_.Cancel();
   resolver_->Reject(
       MakeGarbageCollected<DOMException>(DOMExceptionCode::kAbortError));
+
+  ScriptState* script_state =
+      callback_->CallbackRelevantScriptStateOrReportError("DOMTask", "Abort");
+  DCHECK(script_state && script_state->ContextIsValid());
+  probe::AsyncTaskCanceled(ExecutionContext::From(script_state),
+                           &async_task_id_);
 }
 
 }  // namespace blink

third_party/blink/renderer/modules/scheduler/dom_task.h

@@ -7,6 +7,7 @@
 
 #include "base/time/time.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_promise_resolver.h"
+#include "third_party/blink/renderer/core/probe/async_task_id.h"
 #include "third_party/blink/renderer/platform/heap/handle.h"
 #include "third_party/blink/renderer/platform/scheduler/public/post_cancellable_task.h"
 
@@ -45,6 +46,7 @@ class DOMTask final : public GarbageCollected<DOMTask> {
   Member<V8Function> callback_;
   HeapVector<ScriptValue> arguments_;
   Member<ScriptPromiseResolver> resolver_;
+  probe::AsyncTaskId async_task_id_;
 };
 
 }  // namespace blink