diff --git a/dom/media/gtest/moz.build b/dom/media/gtest/moz.build
index c66ac4a9437f..595a530d12fc 100644
--- a/dom/media/gtest/moz.build
+++ b/dom/media/gtest/moz.build
@@ -19,7 +19,6 @@ UNIFIED_SOURCES += [
     'TestMediaDataDecoder.cpp',
     'TestMediaEventSource.cpp',
     'TestMediaMIMETypes.cpp',
-    'TestMozPromise.cpp',
     'TestMP3Demuxer.cpp',
     'TestMP4Demuxer.cpp',
     'TestRust.cpp',
diff --git a/ipc/ipdl/test/cxx/TestAsyncReturns.cpp b/ipc/ipdl/test/cxx/TestAsyncReturns.cpp
index 9370c0c50527..471c003fdac7 100644
--- a/ipc/ipdl/test/cxx/TestAsyncReturns.cpp
+++ b/ipc/ipdl/test/cxx/TestAsyncReturns.cpp
@@ -27,10 +27,7 @@ TestAsyncReturnsParent::~TestAsyncReturnsParent()
 void
 TestAsyncReturnsParent::Main()
 {
-  if (!AbstractThread::MainThread()) {
-    fail("AbstractThread not initalized");
-  }
-  SendNoReturn()->Then(AbstractThread::MainThread(), __func__,
+  SendNoReturn()->Then(MessageLoop::current()->SerialEventTarget(), __func__,
                        [](bool unused) {
                          fail("resolve handler should not be called");
                        },
@@ -42,7 +39,7 @@ TestAsyncReturnsParent::Main()
                          }
                          passed("reject handler called on channel close");
                        });
-  SendPing()->Then(AbstractThread::MainThread(), __func__,
+  SendPing()->Then(MessageLoop::current()->SerialEventTarget(), __func__,
                    [this](bool one) {
                      if (one) {
                        passed("take one argument");
@@ -88,10 +85,7 @@ TestAsyncReturnsChild::RecvNoReturn(NoReturnResolver&& aResolve)
 mozilla::ipc::IPCResult
 TestAsyncReturnsChild::RecvPing(PingResolver&& aResolve)
 {
-  if (!AbstractThread::MainThread()) {
-    fail("AbstractThread not initalized");
-  }
-  SendPong()->Then(AbstractThread::MainThread(), __func__,
+  SendPong()->Then(MessageLoop::current()->SerialEventTarget(), __func__,
                    [aResolve](const Tuple<uint32_t, uint32_t>& aParam) {
                      if (Get<0>(aParam) == sMagic1 && Get<1>(aParam) == sMagic2) {
                        passed("take two arguments");
diff --git a/dom/media/gtest/TestMozPromise.cpp b/xpcom/tests/gtest/TestMozPromise.cpp
similarity index 95%
rename from dom/media/gtest/TestMozPromise.cpp
rename to xpcom/tests/gtest/TestMozPromise.cpp
index 1267fbede496..0d82fc9fdad6 100644
--- a/dom/media/gtest/TestMozPromise.cpp
+++ b/xpcom/tests/gtest/TestMozPromise.cpp
@@ -5,6 +5,8 @@
 
 #include "gtest/gtest.h"
 
+#include "base/message_loop.h"
+
 #include "mozilla/TaskQueue.h"
 #include "mozilla/MozPromise.h"
 
@@ -407,4 +409,24 @@ TEST(MozPromise, HeterogeneousChaining)
     });
 }
 
+TEST(MozPromise, XPCOMEventTarget)
+{
+  TestPromise::CreateAndResolve(42, __func__)->Then(GetCurrentThreadSerialEventTarget(), __func__,
+    [] (int aResolveValue) -> void { EXPECT_EQ(aResolveValue, 42); },
+    DO_FAIL);
+
+  // Spin the event loop.
+  NS_ProcessPendingEvents(nullptr);
+}
+
+TEST(MozPromise, MessageLoopEventTarget)
+{
+  TestPromise::CreateAndResolve(42, __func__)->Then(MessageLoop::current()->SerialEventTarget(), __func__,
+    [] (int aResolveValue) -> void { EXPECT_EQ(aResolveValue, 42); },
+    DO_FAIL);
+
+  // Spin the event loop.
+  NS_ProcessPendingEvents(nullptr);
+}
+
 #undef DO_FAIL
diff --git a/xpcom/tests/gtest/moz.build b/xpcom/tests/gtest/moz.build
index c49af4dc49ca..c1a4fe02201a 100644
--- a/xpcom/tests/gtest/moz.build
+++ b/xpcom/tests/gtest/moz.build
@@ -22,6 +22,7 @@ UNIFIED_SOURCES += [
     'TestFile.cpp',
     'TestGCPostBarriers.cpp',
     'TestID.cpp',
+    'TestMozPromise.cpp',
     'TestMultiplexInputStream.cpp',
     'TestNsDeque.cpp',
     'TestNSPRLogModulesParser.cpp',
@@ -85,3 +86,5 @@ LOCAL_INCLUDES += [
 ]
 
 FINAL_LIBRARY = 'xul-gtest'
+
+include('/ipc/chromium/chromium-config.mozbuild')