--- a/dom/media/webspeech/synth/SpeechSynthesis.cpp
+++ b/dom/media/webspeech/synth/SpeechSynthesis.cpp
@@ -269,18 +269,20 @@ SpeechSynthesis::GetVoices(nsTArray< nsR
   mVoiceCache.Clear();
 
   for (uint32_t i = 0; i < aResult.Length(); i++) {
     SpeechSynthesisVoice* voice = aResult[i];
     mVoiceCache.Put(voice->mUri, voice);
   }
 }
 
-// For testing purposes, allows us to drop anything in the global queue from
-// content, and bring the browser to initial state.
+// For testing purposes, allows us to cancel the current task that is
+// misbehaving, and flush the queue.
 void
-SpeechSynthesis::DropGlobalQueue()
+SpeechSynthesis::ForceEnd()
 {
-  nsSynthVoiceRegistry::GetInstance()->DropGlobalQueue();
+  if (mCurrentTask) {
+    mCurrentTask->ForceEnd();
+  }
 }
 
 } // namespace dom
 } // namespace mozilla

--- a/dom/media/webspeech/synth/SpeechSynthesis.h
+++ b/dom/media/webspeech/synth/SpeechSynthesis.h
@@ -49,17 +49,17 @@ public:
   void Pause();
 
   void Resume();
 
   void OnEnd(const nsSpeechTask* aTask);
 
   void GetVoices(nsTArray< nsRefPtr<SpeechSynthesisVoice> >& aResult);
 
-  void DropGlobalQueue();
+  void ForceEnd();
 
 private:
   virtual ~SpeechSynthesis();
 
   void AdvanceQueue();
 
   nsCOMPtr<nsPIDOMWindow> mParent;
 

--- a/dom/media/webspeech/synth/ipc/PSpeechSynthesis.ipdl
+++ b/dom/media/webspeech/synth/ipc/PSpeechSynthesis.ipdl
@@ -36,14 +36,12 @@ child:
 parent:
     __delete__();
 
     PSpeechSynthesisRequest(nsString aText, nsString aUri, nsString aLang,
                             float aVolume, float aRate, float aPitch);
 
     sync ReadVoicesAndState() returns (RemoteVoice[] aVoices,
                                        nsString[] aDefaults, bool aIsSpeaking);
-
-    DropGlobalQueue();
 };
 
 } // namespace dom
 } // namespace mozilla

--- a/dom/media/webspeech/synth/ipc/PSpeechSynthesisRequest.ipdl
+++ b/dom/media/webspeech/synth/ipc/PSpeechSynthesisRequest.ipdl
@@ -16,16 +16,18 @@ async protocol PSpeechSynthesisRequest
  parent:
 
   Pause();
 
   Resume();
 
   Cancel();
 
+  ForceEnd();
+
  child:
 
   __delete__(bool aIsError, float aElapsedTime, uint32_t aCharIndex);
 
   OnStart(nsString aUri);
 
   OnPause(float aElapsedTime, uint32_t aCharIndex);
 

--- a/dom/media/webspeech/synth/ipc/SpeechSynthesisChild.cpp
+++ b/dom/media/webspeech/synth/ipc/SpeechSynthesisChild.cpp
@@ -179,10 +179,17 @@ SpeechTaskChild::Resume()
 
 void
 SpeechTaskChild::Cancel()
 {
   MOZ_ASSERT(mActor);
   mActor->SendCancel();
 }
 
+void
+SpeechTaskChild::ForceEnd()
+{
+  MOZ_ASSERT(mActor);
+  mActor->SendForceEnd();
+}
+
 } // namespace dom
 } // namespace mozilla

--- a/dom/media/webspeech/synth/ipc/SpeechSynthesisChild.h
+++ b/dom/media/webspeech/synth/ipc/SpeechSynthesisChild.h
@@ -85,16 +85,18 @@ public:
   NS_IMETHOD SendAudioNative(int16_t* aData, uint32_t aDataLen) override;
 
   virtual void Pause() override;
 
   virtual void Resume() override;
 
   virtual void Cancel() override;
 
+  virtual void ForceEnd() override;
+
 private:
   SpeechSynthesisRequestChild* mActor;
 };
 
 } // namespace dom
 } // namespace mozilla
 
 #endif

--- a/dom/media/webspeech/synth/ipc/SpeechSynthesisParent.cpp
+++ b/dom/media/webspeech/synth/ipc/SpeechSynthesisParent.cpp
@@ -29,24 +29,16 @@ SpeechSynthesisParent::RecvReadVoicesAnd
                                               InfallibleTArray<nsString>* aDefaults,
                                               bool* aIsSpeaking)
 {
   nsSynthVoiceRegistry::GetInstance()->SendVoicesAndState(aVoices, aDefaults,
                                                           aIsSpeaking);
   return true;
 }
 
-bool
-SpeechSynthesisParent::RecvDropGlobalQueue()
-{
-  nsSynthVoiceRegistry::GetInstance()->DropGlobalQueue();
-
-  return true;
-}
-
 PSpeechSynthesisRequestParent*
 SpeechSynthesisParent::AllocPSpeechSynthesisRequestParent(const nsString& aText,
                                                           const nsString& aLang,
                                                           const nsString& aUri,
                                                           const float& aVolume,
                                                           const float& aRate,
                                                           const float& aPitch)
 {
@@ -122,16 +114,24 @@ SpeechSynthesisRequestParent::RecvResume
 bool
 SpeechSynthesisRequestParent::RecvCancel()
 {
   MOZ_ASSERT(mTask);
   mTask->Cancel();
   return true;
 }
 
+bool
+SpeechSynthesisRequestParent::RecvForceEnd()
+{
+  MOZ_ASSERT(mTask);
+  mTask->ForceEnd();
+  return true;
+}
+
 // SpeechTaskParent
 
 nsresult
 SpeechTaskParent::DispatchStartImpl(const nsAString& aUri)
 {
   MOZ_ASSERT(mActor);
   if(NS_WARN_IF(!(mActor->SendOnStart(nsString(aUri))))) {
     return NS_ERROR_FAILURE;

--- a/dom/media/webspeech/synth/ipc/SpeechSynthesisParent.h
+++ b/dom/media/webspeech/synth/ipc/SpeechSynthesisParent.h
@@ -23,18 +23,16 @@ class SpeechSynthesisParent : public PSp
 
 public:
   virtual void ActorDestroy(ActorDestroyReason aWhy) override;
 
   bool RecvReadVoicesAndState(InfallibleTArray<RemoteVoice>* aVoices,
                               InfallibleTArray<nsString>* aDefaults,
                               bool* aIsSpeaking) override;
 
-  bool RecvDropGlobalQueue() override;
-
 protected:
   SpeechSynthesisParent();
   virtual ~SpeechSynthesisParent();
   PSpeechSynthesisRequestParent* AllocPSpeechSynthesisRequestParent(const nsString& aText,
                                                                     const nsString& aLang,
                                                                     const nsString& aUri,
                                                                     const float& aVolume,
                                                                     const float& aRate,
@@ -64,16 +62,18 @@ protected:
 
   virtual void ActorDestroy(ActorDestroyReason aWhy) override;
 
   virtual bool RecvPause() override;
 
   virtual bool RecvResume() override;
 
   virtual bool RecvCancel() override;
+
+  virtual bool RecvForceEnd() override;
 };
 
 class SpeechTaskParent : public nsSpeechTask
 {
   friend class SpeechSynthesisRequestParent;
 public:
   SpeechTaskParent(float aVolume, const nsAString& aUtterance)
     : nsSpeechTask(aVolume, aUtterance) {}

--- a/dom/media/webspeech/synth/nsSpeechTask.cpp
+++ b/dom/media/webspeech/synth/nsSpeechTask.cpp
@@ -608,16 +608,30 @@ nsSpeechTask::Cancel()
     mPreCanceled = true;
   }
 
   if (!mIndirectAudio) {
     DispatchEndInner(GetCurrentTime(), GetCurrentCharOffset());
   }
 }
 
+void
+nsSpeechTask::ForceEnd()
+{
+  if (mStream) {
+    mStream->ChangeExplicitBlockerCount(1);
+  }
+
+  if (!mInited) {
+    mPreCanceled = true;
+  }
+
+  DispatchEndInner(GetCurrentTime(), GetCurrentCharOffset());
+}
+
 float
 nsSpeechTask::GetCurrentTime()
 {
   return mStream ? (float)(mStream->GetCurrentTime() / 1000000.0) : 0;
 }
 
 uint32_t
 nsSpeechTask::GetCurrentCharOffset()

--- a/dom/media/webspeech/synth/nsSpeechTask.h
+++ b/dom/media/webspeech/synth/nsSpeechTask.h
@@ -32,16 +32,18 @@ public:
   nsSpeechTask(float aVolume, const nsAString& aText);
 
   virtual void Pause();
 
   virtual void Resume();
 
   virtual void Cancel();
 
+  virtual void ForceEnd();
+
   float GetCurrentTime();
 
   uint32_t GetCurrentCharOffset();
 
   void SetSpeechSynthesis(SpeechSynthesis* aSpeechSynthesis);
 
   void Init(ProcessedMediaStream* aStream);
 

--- a/dom/media/webspeech/synth/nsSynthVoiceRegistry.cpp
+++ b/dom/media/webspeech/synth/nsSynthVoiceRegistry.cpp
@@ -752,27 +752,16 @@ nsSynthVoiceRegistry::SetIsSpeaking(bool
   nsTArray<SpeechSynthesisParent*> ssplist;
   GetAllSpeechSynthActors(ssplist);
   for (uint32_t i = 0; i < ssplist.Length(); ++i) {
     unused << ssplist[i]->SendIsSpeakingChanged(aIsSpeaking);
   }
 }
 
 void
-nsSynthVoiceRegistry::DropGlobalQueue()
-{
-  if (XRE_IsParentProcess()) {
-    mGlobalQueue.Clear();
-    SetIsSpeaking(false);
-  } else {
-    mSpeechSynthChild->SendDropGlobalQueue();
-  }
-}
-
-void
 nsSynthVoiceRegistry::SpeakImpl(VoiceData* aVoice,
                                 nsSpeechTask* aTask,
                                 const nsAString& aText,
                                 const float& aVolume,
                                 const float& aRate,
                                 const float& aPitch)
 {
   LOG(LogLevel::Debug,

--- a/dom/media/webspeech/synth/nsSynthVoiceRegistry.h
+++ b/dom/media/webspeech/synth/nsSynthVoiceRegistry.h
@@ -47,18 +47,16 @@ public:
   void SpeakNext();
 
   void ResumeQueue();
 
   bool IsSpeaking();
 
   void SetIsSpeaking(bool aIsSpeaking);
 
-  void DropGlobalQueue();
-
   static nsSynthVoiceRegistry* GetInstance();
 
   static already_AddRefed<nsSynthVoiceRegistry> GetInstanceForService();
 
   static void RecvRemoveVoice(const nsAString& aUri);
 
   static void RecvAddVoice(const RemoteVoice& aVoice);
 

--- a/dom/webidl/SpeechSynthesis.webidl
+++ b/dom/webidl/SpeechSynthesis.webidl
@@ -20,10 +20,11 @@ interface SpeechSynthesis {
   void speak(SpeechSynthesisUtterance utterance);
   void cancel();
   void pause();
   [UnsafeInPrerendering]
   void resume();
   sequence<SpeechSynthesisVoice> getVoices();
 
   [ChromeOnly]
-  void dropGlobalQueue();
+  // Force an utterance to end. Circumvents bad speech service implementations.
+  void forceEnd();
 };