Issue #2435 - Implement notifying of rejected promises

Based-on: m-c 1362272

xpcom/base/CycleCollectedJSContext.h

@@ -12,6 +12,7 @@
 #include "mozilla/mozalloc.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/SegmentedVector.h"
+#include "mozilla/dom/Promise.h"
 #include "jsapi.h"
 #include "jsfriendapi.h"
 
@@ -474,6 +475,47 @@ private:
 
   uint32_t mMicroTaskRecursionDepth;
 
+  // This implements about-to-be-notified rejected promises list in the spec.
+  // https://html.spec.whatwg.org/multipage/webappapis.html#about-to-be-notified-rejected-promises-list
+  typedef nsTArray<RefPtr<dom::Promise>> PromiseArray;
+  PromiseArray mAboutToBeNotifiedRejectedPromises;
+
+  // This is for the "outstanding rejected promises weak set" in the spec,
+  // https://html.spec.whatwg.org/multipage/webappapis.html#outstanding-rejected-promises-weak-set
+  // We use different data structure and opposite logic here to achieve the same
+  // effect. Basically this is used for tracking the rejected promise that does
+  // NOT need firing a rejectionhandled event. We will check the table to see if
+  // firing rejectionhandled event is required when a rejected promise is being
+  // handled.
+  //
+  // The rejected promise will be stored in the table if
+  // - it is unhandled, and
+  // - The unhandledrejection is not yet fired.
+  //
+  // And be removed when
+  // - it is handled, or
+  // - A unhandledrejection is fired and it isn't being handled in event
+  // handler.
+  typedef nsRefPtrHashtable<nsUint64HashKey, dom::Promise> PromiseHashtable;
+  PromiseHashtable mPendingUnhandledRejections;
+
+  class NotifyUnhandledRejections final : public CancelableRunnable {
+   public:
+    NotifyUnhandledRejections(CycleCollectedJSContext* aCx,
+                              PromiseArray&& aPromises)
+        : CancelableRunnable(),
+          mCx(aCx),
+          mUnhandledRejections(std::move(aPromises)) {}
+
+    NS_IMETHOD Run() final;
+
+    nsresult Cancel() final;
+
+   private:
+    CycleCollectedJSContext* mCx;
+    PromiseArray mUnhandledRejections;
+  };
+
   OOMState mOutOfMemoryState;
   OOMState mLargeAllocationFailureState;