Add {CancelableTaskManager} to handle {Cancelable} concurrent tasks.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index bb0cdf44bb9a878804bf94cff20d58925a8d5d8a..750d92ed2d852ec7a1b2f4383b04c2102c424042 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1880,6 +1880,16 @@ void Isolate::ClearSerializerData() {
 void Isolate::Deinit() {
   TRACE_ISOLATE(deinit);
 
+  while (true) {

[Hannes Payer (out of office), 2015/11/04 23:19:00]

Why the while loop?

+    base::LockGuard<base::Mutex> guard(&isolate_mutex_);
+    for (Cancelable* task : cancelable_tasks_) {
+      if (task->CancelForShutdown()) {
+        cancelable_tasks_.erase(task);
+      }
+    }
+    if (cancelable_tasks_.empty()) break;
+  }
+
   debug()->Unload();
 
   FreeThreadResources();
@@ -1920,11 +1930,6 @@ void Isolate::Deinit() {
   delete basic_block_profiler_;
   basic_block_profiler_ = NULL;
 
-  for (Cancelable* task : cancelable_tasks_) {
-    task->Cancel();
-  }
-  cancelable_tasks_.clear();
-
   heap_.TearDown();
   logger_->TearDown();
 
@@ -2799,11 +2804,13 @@ void Isolate::CheckDetachedContextsAfterGC() {
 
 
 void Isolate::RegisterCancelableTask(Cancelable* task) {
+  base::LockGuard<base::Mutex> guard(&isolate_mutex_);

[Hannes Payer (out of office), 2015/11/04 23:19:00]

Are these methods not always called from the main thread? Why the mutex?

   cancelable_tasks_.insert(task);
 }
 
 
 void Isolate::RemoveCancelableTask(Cancelable* task) {
+  base::LockGuard<base::Mutex> guard(&isolate_mutex_);
   auto removed = cancelable_tasks_.erase(task);
   USE(removed);
   DCHECK(removed == 1);