Introduce MicrotasksCompletedCallback.

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 2748 matching lines @@
   DCHECK(queue->get(num_tasks)->IsUndefined());
   queue->set(num_tasks, *microtask);
   set_pending_microtask_count(num_tasks + 1);
 }
 
 
 void Isolate::RunMicrotasks() {
   // Increase call depth to prevent recursive callbacks.
   v8::Isolate::SuppressMicrotaskExecutionScope suppress(
       reinterpret_cast<v8::Isolate*>(this));
+  RunMicrotasksInternal();
+  FireMicrotasksCompletedCallback();
+}
 
+
+void Isolate::RunMicrotasksInternal() {
   while (pending_microtask_count() > 0) {
     HandleScope scope(this);
     int num_tasks = pending_microtask_count();
     Handle<FixedArray> queue(heap()->microtask_queue(), this);
     DCHECK(num_tasks <= queue->length());
     set_pending_microtask_count(0);
     heap()->set_microtask_queue(heap()->empty_fixed_array());
 
     for (int i = 0; i < num_tasks; i++) {
       HandleScope scope(this);
@@ skipping 21 matching lines @@
         v8::MicrotaskCallback callback =
             v8::ToCData<v8::MicrotaskCallback>(callback_info->callback());
         void* data = v8::ToCData<void*>(callback_info->data());
         callback(data);
       }
     }
   }
 }
 
 
+void Isolate::AddMicrotasksCompletedCallback(
+    MicrotasksCompletedCallback callback) {
+  for (int i = 0; i < microtasks_completed_callbacks_.length(); i++) {
+    if (callback == microtasks_completed_callbacks_.at(i)) return;
+  }
+  microtasks_completed_callbacks_.Add(callback);
+}
+
+
+void Isolate::RemoveMicrotasksCompletedCallback(
+    MicrotasksCompletedCallback callback) {
+  for (int i = 0; i < microtasks_completed_callbacks_.length(); i++) {
+    if (callback == microtasks_completed_callbacks_.at(i)) {
+      microtasks_completed_callbacks_.Remove(i);
+    }
+  }
+}
+
+
+void Isolate::FireMicrotasksCompletedCallback() {
+  for (int i = 0; i < microtasks_completed_callbacks_.length(); i++) {
+    microtasks_completed_callbacks_.at(i)(reinterpret_cast<v8::Isolate*>(this));
+  }
+}
+
+
 void Isolate::SetUseCounterCallback(v8::Isolate::UseCounterCallback callback) {
   DCHECK(!use_counter_callback_);
   use_counter_callback_ = callback;
 }
 
 
 void Isolate::CountUsage(v8::Isolate::UseCounterFeature feature) {
   // The counter callback may cause the embedder to call into V8, which is not
   // generally possible during GC.
   if (heap_.gc_state() == Heap::NOT_IN_GC) {
@@ skipping 120 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8