--- a/netwerk/protocol/http/HttpChannelChild.cpp
+++ b/netwerk/protocol/http/HttpChannelChild.cpp
@@ -168,17 +168,17 @@ HttpChannelChild::HttpChannelChild()
   , mCacheFetchCount(0)
   , mCacheExpirationTime(nsICacheEntry::NO_EXPIRATION_TIME)
   , mSendResumeAt(false)
   , mDeletingChannelSent(false)
   , mIPCOpen(false)
   , mKeptAlive(false)
   , mUnknownDecoderInvolved(false)
   , mDivertingToParent(false)
-  , mFlushedForDiversion(eNotFlushed)
+  , mFlushedForDiversion(false)
   , mSuspendSent(false)
   , mSynthesizedResponse(false)
   , mShouldInterceptSubsequentRedirect(false)
   , mRedirectingForSubsequentSynthesizedResponse(false)
   , mPostRedirectChannelShouldIntercept(false)
   , mPostRedirectChannelShouldUpgrade(false)
   , mShouldParentIntercept(false)
   , mSuspendParentAfterSynthesizeResponse(false)
@@ -488,17 +488,17 @@ HttpChannelChild::RecvOnStartRequest(con
                                      const int16_t& redirectCount,
                                      const uint32_t& cacheKey,
                                      const nsCString& altDataType,
                                      const int64_t& altDataLen)
 {
   LOG(("HttpChannelChild::RecvOnStartRequest [this=%p]\n", this));
   // mFlushedForDiversion and mDivertingToParent should NEVER be set at this
   // stage, as they are set in the listener's OnStartRequest.
-  MOZ_RELEASE_ASSERT(mFlushedForDiversion == eNotFlushed,
+  MOZ_RELEASE_ASSERT(!mFlushedForDiversion,
     "mFlushedForDiversion should be unset before OnStartRequest!");
   MOZ_RELEASE_ASSERT(!mDivertingToParent,
     "mDivertingToParent should be unset before OnStartRequest!");
 
 
   mRedirectCount = redirectCount;
 
   mEventQ->RunOrEnqueue(new StartRequestEvent(this, channelStatus, responseHead,
@@ -549,17 +549,17 @@ HttpChannelChild::OnStartRequest(const n
                                  const uint32_t& cacheKey,
                                  const nsCString& altDataType,
                                  const int64_t& altDataLen)
 {
   LOG(("HttpChannelChild::OnStartRequest [this=%p]\n", this));
 
   // mFlushedForDiversion and mDivertingToParent should NEVER be set at this
   // stage, as they are set in the listener's OnStartRequest.
-  MOZ_RELEASE_ASSERT(mFlushedForDiversion == eNotFlushed,
+  MOZ_RELEASE_ASSERT(!mFlushedForDiversion,
     "mFlushedForDiversion should be unset before OnStartRequest!");
   MOZ_RELEASE_ASSERT(!mDivertingToParent,
     "mDivertingToParent should be unset before OnStartRequest!");
 
   if (!mCanceled && NS_SUCCEEDED(mStatus)) {
     mStatus = channelStatus;
   }
 
@@ -610,16 +610,18 @@ HttpChannelChild::OnStartRequest(const n
   //
   // gHttpHandler->OnExamineResponse(this);
 
   mTracingEnabled = false;
 
   DoOnStartRequest(this, mListenerContext);
 }
 
+namespace {
+
 class SyntheticDiversionListener final : public nsIStreamListener
 {
   RefPtr<HttpChannelChild> mChannel;
 
   ~SyntheticDiversionListener()
   {
   }
 
@@ -637,17 +639,16 @@ public:
     return NS_OK;
   }
 
   NS_IMETHOD
   OnStopRequest(nsIRequest* aRequest, nsISupports* aContext,
                 nsresult aStatus) override
   {
     mChannel->SendDivertOnStopRequest(aStatus);
-    mChannel->MaybeSendDivertComplete();
     return NS_OK;
   }
 
   NS_IMETHOD
   OnDataAvailable(nsIRequest* aRequest, nsISupports* aContext,
                   nsIInputStream* aInputStream, uint64_t aOffset,
                   uint32_t aCount) override
   {
@@ -662,16 +663,18 @@ public:
     return NS_OK;
   }
 
   NS_DECL_ISUPPORTS
 };
 
 NS_IMPL_ISUPPORTS(SyntheticDiversionListener, nsIStreamListener);
 
+} // anonymous namespace
+
 void
 HttpChannelChild::DoOnStartRequest(nsIRequest* aRequest, nsISupports* aContext)
 {
   LOG(("HttpChannelChild::DoOnStartRequest [this=%p]\n", this));
 
   // In theory mListener should not be null, but in practice sometimes it is.
   MOZ_ASSERT(mListener);
   if (!mListener) {
@@ -761,17 +764,17 @@ void
 HttpChannelChild::ProcessOnTransportAndData(const nsresult& aChannelStatus,
                                             const nsresult& aTransportStatus,
                                             const uint64_t& aOffset,
                                             const uint32_t& aCount,
                                             const nsCString& aData)
 {
   LOG(("HttpChannelChild::ProcessOnTransportAndData [this=%p]\n", this));
   MOZ_ASSERT(OnSocketThread());
-  MOZ_RELEASE_ASSERT(mFlushedForDiversion == eNotFlushed,
+  MOZ_RELEASE_ASSERT(!mFlushedForDiversion,
                      "Should not be receiving any more callbacks from parent!");
   mEventQ->RunOrEnqueue(new TransportAndDataEvent(this, aChannelStatus,
                                                   aTransportStatus, aData,
                                                   aOffset, aCount),
                         mDivertingToParent);
 }
 
 class MaybeDivertOnDataHttpEvent : public NeckoTargetChannelEvent<HttpChannelChild>
@@ -820,17 +823,17 @@ HttpChannelChild::OnTransportAndData(con
 
   if (!mCanceled && NS_SUCCEEDED(mStatus)) {
     mStatus = channelStatus;
   }
 
   // For diversion to parent, just SendDivertOnDataAvailable.
   if (mDivertingToParent) {
     MOZ_ASSERT(NS_IsMainThread());
-    MOZ_RELEASE_ASSERT(mFlushedForDiversion == eNotFlushed,
+    MOZ_RELEASE_ASSERT(!mFlushedForDiversion,
       "Should not be processing any more callbacks from parent!");
 
     SendDivertOnDataAvailable(data, offset, count);
     return;
   }
 
   if (mCanceled)
     return;
@@ -989,17 +992,17 @@ class StopRequestEvent : public NeckoTar
 };
 
 void
 HttpChannelChild::ProcessOnStopRequest(const nsresult& aChannelStatus,
                                        const ResourceTimingStruct& aTiming)
 {
   LOG(("HttpChannelChild::ProcessOnStopRequest [this=%p]\n", this));
   MOZ_ASSERT(OnSocketThread());
-  MOZ_RELEASE_ASSERT(mFlushedForDiversion == eNotFlushed,
+  MOZ_RELEASE_ASSERT(!mFlushedForDiversion,
     "Should not be receiving any more callbacks from parent!");
 
   mEventQ->RunOrEnqueue(new StopRequestEvent(this, aChannelStatus, aTiming),
                         mDivertingToParent);
 }
 
 class MaybeDivertOnStopHttpEvent : public NeckoTargetChannelEvent<HttpChannelChild>
 {
@@ -1023,51 +1026,32 @@ void
 HttpChannelChild::MaybeDivertOnStop(const nsresult& aChannelStatus)
 {
   LOG(("HttpChannelChild::MaybeDivertOnStop [this=%p, "
        "mDivertingToParent=%d status=%" PRIx32 "]", this,
        static_cast<bool>(mDivertingToParent),
        static_cast<uint32_t>(aChannelStatus)));
   if (mDivertingToParent) {
     SendDivertOnStopRequest(aChannelStatus);
-    MaybeSendDivertComplete();
   }
 }
 
 void
-HttpChannelChild::MaybeSendDivertComplete()
-{
-  if (mFlushedForDiversion == eNotFlushed) {
-    mFlushedForDiversion = eReadyToBeFlushed;
-    return;
-  }
-
-  if (mFlushedForDiversion == ePendingToBeFlushed) {
-    mFlushedForDiversion = eFlushed;
-    SendDivertComplete();
-    return;
-  }
-
-  MOZ_CRASH("We should not be already in this state!");
-}
-
-void
 HttpChannelChild::OnStopRequest(const nsresult& channelStatus,
                                 const ResourceTimingStruct& timing)
 {
   LOG(("HttpChannelChild::OnStopRequest [this=%p status=%" PRIx32 "]\n",
        this, static_cast<uint32_t>(channelStatus)));
   MOZ_ASSERT(NS_IsMainThread());
 
   if (mDivertingToParent) {
-    MOZ_RELEASE_ASSERT(mFlushedForDiversion == eNotFlushed,
+    MOZ_RELEASE_ASSERT(!mFlushedForDiversion,
       "Should not be processing any more callbacks from parent!");
 
     SendDivertOnStopRequest(channelStatus);
-    MaybeSendDivertComplete();
     return;
   }
 
   if (mUnknownDecoderInvolved) {
    LOG(("UnknownDecoder is involved queue OnStopRequest call. [this=%p]",
         this));
     MOZ_ASSERT(NS_IsMainThread());
     mUnknownDecoderEventQ.AppendElement(
@@ -1857,23 +1841,19 @@ void
 HttpChannelChild::FlushedForDiversion()
 {
   LOG(("HttpChannelChild::FlushedForDiversion [this=%p]\n", this));
   MOZ_RELEASE_ASSERT(mDivertingToParent);
 
   // Once this is set, it should not be unset before HttpChannelChild is taken
   // down. After it is set, no OnStart/OnData/OnStop callbacks should be
   // received from the parent channel, nor dequeued from the ChannelEventQueue.
-
-  if (mFlushedForDiversion == eReadyToBeFlushed) {
-    mFlushedForDiversion = eFlushed;
-    SendDivertComplete();
-  } else {
-    mFlushedForDiversion = ePendingToBeFlushed;
-  }
+  mFlushedForDiversion = true;
+
+  SendDivertComplete();
 }
 
 void
 HttpChannelChild::ProcessSetClassifierMatchedInfo(const nsCString& aList,
                                                   const nsCString& aProvider,
                                                   const nsCString& aFullHash)
 {
   LOG(("HttpChannelChild::ProcessSetClassifierMatchedInfo [this=%p]\n", this));

--- a/netwerk/protocol/http/HttpChannelChild.h
+++ b/netwerk/protocol/http/HttpChannelChild.h
@@ -314,41 +314,19 @@ private:
   // If nsUnknownDecoder is involved OnStartRequest call will be delayed and
   // this queue keeps OnDataAvailable data until OnStartRequest is finally
   // called.
   nsTArray<UniquePtr<ChannelEvent>> mUnknownDecoderEventQ;
   Atomic<bool, ReleaseAcquire> mUnknownDecoderInvolved;
 
   // Once set, OnData and possibly OnStop will be diverted to the parent.
   Atomic<bool, ReleaseAcquire> mDivertingToParent;
-
-  enum FlushedForDiversionEnum {
-    // This is the initial state.
-    eNotFlushed,
-
-    // This is set when SendOnStopRequest() is called and the previous state was
-    // eNotFlushed. FlushedForDiversion() has not been called yet, but when,
-    // eventually, it will be, SendDivertComplete() can immediately called.
-    eReadyToBeFlushed,
-
-    // This is set by FlushedForDiversion() when SetOnStopRequest() has not been
-    // called yet. When finally SetOnStopRequest() will be called,
-    // SendDivertComplete() will be executed as well.
-    ePendingToBeFlushed,
-
-    // This is the final step. No OnStart/OnData/OnStop callbacks should be
-    // received from the parent channel, nor dequeued from the
-    // ChannelEventQueue.
-    eFlushed,
-  };
-
-  // Atomic becuase it can be touched onSocketThread() for debugging reasons
-  // only.
-  Atomic<FlushedForDiversionEnum, ReleaseAcquire> mFlushedForDiversion;
-
+  // Once set, no OnStart/OnData/OnStop callbacks should be received from the
+  // parent channel, nor dequeued from the ChannelEventQueue.
+  Atomic<bool, ReleaseAcquire> mFlushedForDiversion;
   // Set if SendSuspend is called. Determines if SendResume is needed when
   // diverting callbacks to parent.
   bool mSuspendSent;
 
   // Set if a response was synthesized, indicating that any forthcoming redirects
   // should be intercepted.
   bool mSynthesizedResponse;
 
@@ -457,34 +435,28 @@ private:
                            const nsHttpResponseHead* responseHead);
 
   // Override the default security info pointer during a non-IPC redirection.
   void OverrideSecurityInfoForNonIPCRedirect(nsISupports* securityInfo);
 
   // Collect telemetry for the successful rate of OMT.
   void CollectOMTTelemetry();
 
-  // When SendDivertOnStopRequest() is called, this method is used to check
-  // mFlushedForDiversion and maybe call SendDivertComplete(). See
-  // mFlushedForDiversion state.
-  void MaybeSendDivertComplete();
-
   // The result of RetargetDeliveryTo for this channel.
   // |notRequested| represents OMT is not requested by the channel owner.
   LABELS_HTTP_CHILD_OMT_STATS mOMTResult = LABELS_HTTP_CHILD_OMT_STATS::notRequested;
 
   friend class AssociateApplicationCacheEvent;
   friend class StartRequestEvent;
   friend class StopRequestEvent;
   friend class TransportAndDataEvent;
   friend class MaybeDivertOnDataHttpEvent;
   friend class MaybeDivertOnStopHttpEvent;
   friend class ProgressEvent;
   friend class StatusEvent;
-  friend class SyntheticDiversionListener;
   friend class FailedAsyncOpenEvent;
   friend class Redirect1Event;
   friend class Redirect3Event;
   friend class DeleteSelfEvent;
   friend class HttpFlushedForDiversionEvent;
   friend class CancelEvent;
   friend class HttpAsyncAborter<HttpChannelChild>;
   friend class InterceptStreamListener;