Introduce Promise::MarkAsHandled

We are migrating streams implementation from JavaScript (v8Extra) to
C++. One of missing features is an ability to set
promise.[[PromiseIsHandled]] to true, used for example in
https://streams.spec.whatwg.org/#rs-pipe-through. This CL introduces
the feature.

Bug: chromium:894357, chromium:888154, chromium:902633
Change-Id: If6487b29a74a212761e6d2ef04ef3ca0e6957dce
Reviewed-on: https://chromium-review.googlesource.com/c/1322296Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57370}

include/v8.h

@@ -4153,6 +4153,11 @@ class V8_EXPORT Promise : public Object {
    */
   PromiseState State();
 
+  /**
+   * Marks this promise as handled to avoid reporting unhandled rejections.
+   */
+  void MarkAsHandled();
+
   V8_INLINE static Promise* Cast(Value* obj);
 
   static const int kEmbedderFieldCount = V8_PROMISE_INTERNAL_FIELD_COUNT;

src/api.cc

@@ -7272,6 +7272,11 @@ Promise::PromiseState Promise::State() {
   return static_cast<PromiseState>(js_promise->status());
 }
 
+void Promise::MarkAsHandled() {
+  i::Handle<i::JSPromise> js_promise = Utils::OpenHandle(this);
+  js_promise->set_has_handler(true);
+}
+
 Local<Value> Proxy::GetTarget() {
   i::Handle<i::JSProxy> self = Utils::OpenHandle(this);
   i::Handle<i::Object> target(self->target(), self->GetIsolate());

test/cctest/test-api.cc

@@ -18507,6 +18507,34 @@ TEST(PromiseRejectIsSharedCrossOrigin) {
   CHECK(promise_reject_is_shared_cross_origin);
 }
 
+TEST(PromiseRejectMarkAsHandled) {
+  LocalContext env;
+  v8::Isolate* isolate = env->GetIsolate();
+  v8::HandleScope scope(isolate);
+
+  isolate->SetPromiseRejectCallback(PromiseRejectCallback);
+
+  ResetPromiseStates();
+
+  // Create promise p0.
+  CompileRun(
+      "var reject;            \n"
+      "var p0 = new Promise(  \n"
+      "  function(res, rej) { \n"
+      "    reject = rej;      \n"
+      "  }                    \n"
+      ");                     \n");
+  CHECK(!GetPromise("p0")->HasHandler());
+  CHECK_EQ(0, promise_reject_counter);
+  CHECK_EQ(0, promise_revoke_counter);
+  GetPromise("p0")->MarkAsHandled();
+
+  // Reject p0. promise_reject_counter shouldn't be incremented because
+  // it's marked as handled.
+  CompileRun("reject('ppp');");
+  CHECK_EQ(0, promise_reject_counter);
+  CHECK_EQ(0, promise_revoke_counter);
+}
 void PromiseRejectCallbackConstructError(
     v8::PromiseRejectMessage reject_message) {
   v8::Local<v8::Context> context = CcTest::isolate()->GetCurrentContext();