Backed out changeset d04e34978e0b (bug 1605072) for test crashes e.g [@ mozilla::PreallocatedProcessManagerImpl::AddBlocker(mozilla::dom::ContentParent*)] on a CLOSED TREE

docshell/base/CanonicalBrowsingContext.cpp

@@ -274,6 +274,26 @@ void CanonicalBrowsingContext::LoadURI(const nsAString& aURI,
   LoadURI(nullptr, loadState, true);
 }
 
+namespace {
+
+using NewOrUsedPromise = MozPromise<RefPtr<ContentParent>, nsresult, false>;
+
+// NOTE: This method is currently a dummy, and always actually spawns sync. It
+// mostly exists so I can test out the async API right now.
+RefPtr<NewOrUsedPromise> GetNewOrUsedBrowserProcessAsync(
+    const nsAString& aRemoteType) {
+  RefPtr<ContentParent> contentParent =
+      ContentParent::GetNewOrUsedBrowserProcess(
+          nullptr, aRemoteType, hal::PROCESS_PRIORITY_FOREGROUND, nullptr,
+          false);
+  if (!contentParent) {
+    return NewOrUsedPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
+  }
+  return NewOrUsedPromise::CreateAndResolve(contentParent, __func__);
+}
+
+}  // anonymous namespace
+
 void CanonicalBrowsingContext::PendingRemotenessChange::Complete(
     ContentParent* aContentParent) {
   if (!mPromise) {
@@ -491,18 +511,13 @@ CanonicalBrowsingContext::ChangeFrameRemoteness(const nsAString& aRemoteType,
       new PendingRemotenessChange(this, promise, aPendingSwitchId);
   mPendingRemotenessChange = change;
 
-  ContentParent::GetNewOrUsedBrowserProcessAsync(
-      /* aFrameElement = */ nullptr,
-      /* aRemoteType = */ aRemoteType,
-      /* aPriority = */ hal::PROCESS_PRIORITY_FOREGROUND,
-      /* aOpener = */ nullptr,
-      /* aPreferUsed = */ false)
+  GetNewOrUsedBrowserProcessAsync(aRemoteType)
       ->Then(
           GetMainThreadSerialEventTarget(), __func__,
           [change](ContentParent* aContentParent) {
             change->Complete(aContentParent);
           },
-          [change](LaunchError aError) { change->Cancel(NS_ERROR_FAILURE); });
+          [change](nsresult aRv) { change->Cancel(aRv); });
   return promise.forget();
 }