--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -4184,24 +4184,63 @@ HTMLMediaElement::PrincipalChanged(DOMMe
   LOG(LogLevel::Info, ("HTMLMediaElement %p Stream principal changed.", this));
   nsContentUtils::CombineResourcePrincipals(&mSrcStreamVideoPrincipal,
                                             aStream->GetVideoPrincipal());
 
   LOG(LogLevel::Debug, ("HTMLMediaElement %p Stream video principal changed to "
                         "%p. Waiting for it to reach VideoFrameContainer before "
                         "setting.", this, aStream->GetVideoPrincipal()));
   if (mVideoFrameContainer) {
-    UpdateSrcStreamVideoPrincipal(aStream->GetVideoPrincipal());
+    UpdateSrcStreamVideoPrincipal(mVideoFrameContainer->GetLastPrincipalHandle());
   }
 }
 
 void
-HTMLMediaElement::UpdateSrcStreamVideoPrincipal(nsIPrincipal* aPrincipal)
-{
-  mSrcStreamVideoPrincipal = aPrincipal;
+HTMLMediaElement::UpdateSrcStreamVideoPrincipal(const PrincipalHandle& aPrincipalHandle)
+{
+  nsTArray<RefPtr<VideoStreamTrack>> videoTracks;
+  mSrcStream->GetVideoTracks(videoTracks);
+
+  PrincipalHandle handle(aPrincipalHandle);
+  bool matchesTrackPrincipal = false;
+  for (const RefPtr<VideoStreamTrack>& track : videoTracks) {
+    if (PrincipalHandleMatches(handle,
+                               track->GetPrincipal()) &&
+        !track->Ended()) {
+      // When the PrincipalHandle for the VideoFrameContainer changes to that of
+      // a track in mSrcStream we know that a removed track was displayed but
+      // is no longer so.
+      matchesTrackPrincipal = true;
+      LOG(LogLevel::Debug, ("HTMLMediaElement %p VideoFrameContainer's "
+                            "PrincipalHandle matches track %p. That's all we "
+                            "need.", this, track.get()));
+      break;
+    }
+  }
+
+  if (matchesTrackPrincipal) {
+    mSrcStreamVideoPrincipal = mSrcStream->GetVideoPrincipal();
+  }
+}
+
+void
+HTMLMediaElement::PrincipalHandleChangedForVideoFrameContainer(VideoFrameContainer* aContainer,
+                                                               const PrincipalHandle& aNewPrincipalHandle)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!mSrcStream) {
+    return;
+  }
+
+  LOG(LogLevel::Debug, ("HTMLMediaElement %p PrincipalHandle changed in "
+                        "VideoFrameContainer.",
+                        this));
+
+  UpdateSrcStreamVideoPrincipal(aNewPrincipalHandle);
 }
 
 nsresult HTMLMediaElement::DispatchEvent(const nsAString& aName)
 {
   LOG_EVENT(LogLevel::Debug, ("%p Dispatching event %s", this,
                           NS_ConvertUTF16toUTF8(aName).get()));
 
   // Save events that occur while in the bfcache. These will be dispatched

--- a/dom/html/HTMLMediaElement.h
+++ b/dom/html/HTMLMediaElement.h
@@ -226,17 +226,22 @@ public:
   // Called by the media decoder and the video frame to get the
   // ImageContainer containing the video data.
   B2G_ACL_EXPORT virtual VideoFrameContainer* GetVideoFrameContainer() final override;
   layers::ImageContainer* GetImageContainer();
 
   // From PrincipalChangeObserver<DOMMediaStream>.
   void PrincipalChanged(DOMMediaStream* aStream) override;
 
-  void UpdateSrcStreamVideoPrincipal(nsIPrincipal* aPrincipal);
+  void UpdateSrcStreamVideoPrincipal(const PrincipalHandle& aPrincipalHandle);
+
+  // Called after the MediaStream we're playing rendered a frame to aContainer
+  // with a different principalHandle than the previous frame.
+  void PrincipalHandleChangedForVideoFrameContainer(VideoFrameContainer* aContainer,
+                                                    const PrincipalHandle& aNewPrincipalHandle);
 
   // Dispatch events
   virtual nsresult DispatchAsyncEvent(const nsAString& aName) final override;
 
   // Triggers a recomputation of readyState.
   void UpdateReadyState() override { UpdateReadyStateInternal(); }
 
   // Dispatch events that were raised while in the bfcache

--- a/dom/media/MediaStreamGraph.cpp
+++ b/dom/media/MediaStreamGraph.cpp
@@ -875,16 +875,17 @@ MediaStreamGraphImpl::PlayVideo(MediaStr
 
   if (aStream->mVideoOutputs.IsEmpty())
     return;
 
   TimeStamp currentTimeStamp = CurrentDriver()->GetCurrentTimeStamp();
 
   // Collect any new frames produced in this iteration.
   AutoTArray<ImageContainer::NonOwningImage,4> newImages;
+  PrincipalHandle lastPrincipalHandle = PRINCIPAL_HANDLE_NONE;
   RefPtr<Image> blackImage;
 
   MOZ_ASSERT(mProcessedTime >= aStream->mBufferStartTime, "frame position before buffer?");
   // We only look at the non-blocking interval
   StreamTime frameBufferTime = aStream->GraphTimeToStreamTime(mProcessedTime);
   StreamTime bufferEndTime = aStream->GraphTimeToStreamTime(aStream->mStartBlocking);
   StreamTime start;
   const VideoChunk* chunk;
@@ -938,28 +939,34 @@ MediaStreamGraphImpl::PlayVideo(MediaStr
         }
       }
       if (blackImage) {
         image = blackImage;
       }
     }
     newImages.AppendElement(ImageContainer::NonOwningImage(image, targetTime));
 
+    lastPrincipalHandle = chunk->GetPrincipalHandle();
+
     aStream->mLastPlayedVideoFrame = *frame;
   }
 
   if (!aStream->mLastPlayedVideoFrame.GetImage())
     return;
 
   AutoTArray<ImageContainer::NonOwningImage,4> images;
   bool haveMultipleImages = false;
 
   for (uint32_t i = 0; i < aStream->mVideoOutputs.Length(); ++i) {
     VideoFrameContainer* output = aStream->mVideoOutputs[i];
 
+    bool principalHandleChanged =
+      lastPrincipalHandle != PRINCIPAL_HANDLE_NONE &&
+      lastPrincipalHandle != output->GetLastPrincipalHandle();
+
     // Find previous frames that may still be valid.
     AutoTArray<ImageContainer::OwningImage,4> previousImages;
     output->GetImageContainer()->GetCurrentImages(&previousImages);
     uint32_t j = previousImages.Length();
     if (j) {
       // Re-use the most recent frame before currentTimeStamp and subsequent,
       // always keeping at least one frame.
       do {
@@ -989,16 +996,22 @@ MediaStreamGraphImpl::PlayVideo(MediaStr
                                           image.mTimeStamp, image.mFrameID));
     }
 
     // Add the frames from this iteration.
     for (auto& image : newImages) {
       image.mFrameID = output->NewFrameID();
       images.AppendElement(image);
     }
+
+    if (principalHandleChanged) {
+      output->UpdatePrincipalHandleForFrameID(lastPrincipalHandle,
+                                              newImages.LastElement().mFrameID);
+    }
+
     output->SetCurrentFrames(aStream->mLastPlayedVideoFrame.GetIntrinsicSize(),
                              images);
 
     nsCOMPtr<nsIRunnable> event =
       new VideoFrameContainerInvalidateRunnable(output);
     DispatchToMainThreadAfterStreamStateUpdate(event.forget());
 
     images.ClearAndRetainStorage();

--- a/dom/media/VideoFrameContainer.cpp
+++ b/dom/media/VideoFrameContainer.cpp
@@ -15,25 +15,43 @@ using namespace mozilla::layers;
 
 namespace mozilla {
 
 VideoFrameContainer::VideoFrameContainer(dom::HTMLMediaElement* aElement,
                                          already_AddRefed<ImageContainer> aContainer)
   : mElement(aElement),
     mImageContainer(aContainer), mMutex("nsVideoFrameContainer"),
     mFrameID(0),
-    mIntrinsicSizeChanged(false), mImageSizeChanged(false)
+    mIntrinsicSizeChanged(false), mImageSizeChanged(false),
+    mPendingPrincipalHandle(PRINCIPAL_HANDLE_NONE), mFrameIDForPendingPrincipalHandle(0)
 {
   NS_ASSERTION(aElement, "aElement must not be null");
   NS_ASSERTION(mImageContainer, "aContainer must not be null");
 }
 
 VideoFrameContainer::~VideoFrameContainer()
 {}
 
+PrincipalHandle VideoFrameContainer::GetLastPrincipalHandle()
+{
+  MutexAutoLock lock(mMutex);
+  return mLastPrincipalHandle;
+}
+
+void VideoFrameContainer::UpdatePrincipalHandleForFrameID(const PrincipalHandle& aPrincipalHandle,
+                                                          const ImageContainer::FrameID& aFrameID)
+{
+  MutexAutoLock lock(mMutex);
+  if (mPendingPrincipalHandle == aPrincipalHandle) {
+    return;
+  }
+  mPendingPrincipalHandle = aPrincipalHandle;
+  mFrameIDForPendingPrincipalHandle = aFrameID;
+}
+
 void VideoFrameContainer::SetCurrentFrame(const gfx::IntSize& aIntrinsicSize,
                                           Image* aImage,
                                           const TimeStamp& aTargetTime)
 {
   if (aImage) {
     MutexAutoLock lock(mMutex);
     AutoTArray<ImageContainer::NonOwningImage,1> imageList;
     imageList.AppendElement(
@@ -64,18 +82,43 @@ void VideoFrameContainer::SetCurrentFram
   gfx::IntSize oldFrameSize = mImageContainer->GetCurrentSize();
 
   // When using the OMX decoder, destruction of the current image can indirectly
   //  block on main thread I/O. If we let this happen while holding onto
   //  |mImageContainer|'s lock, then when the main thread then tries to
   //  composite it can then block on |mImageContainer|'s lock, causing a
   //  deadlock. We use this hack to defer the destruction of the current image
   //  until it is safe.
-  nsTArray<ImageContainer::OwningImage> kungFuDeathGrip;
-  mImageContainer->GetCurrentImages(&kungFuDeathGrip);
+  nsTArray<ImageContainer::OwningImage> oldImages;
+  mImageContainer->GetCurrentImages(&oldImages);
+
+  ImageContainer::FrameID lastFrameIDForOldPrincipalHandle =
+    mFrameIDForPendingPrincipalHandle - 1;
+  if (mPendingPrincipalHandle != PRINCIPAL_HANDLE_NONE &&
+       ((!oldImages.IsEmpty() &&
+          oldImages.LastElement().mFrameID >= lastFrameIDForOldPrincipalHandle) ||
+        (!aImages.IsEmpty() &&
+          aImages[0].mFrameID > lastFrameIDForOldPrincipalHandle))) {
+    // We are releasing the last FrameID prior to `lastFrameIDForOldPrincipalHandle`
+    // OR
+    // there are no FrameIDs prior to `lastFrameIDForOldPrincipalHandle` in the new
+    // set of images.
+    // This means that the old principal handle has been flushed out and we can
+    // notify our video element about this change.
+    RefPtr<VideoFrameContainer> self = this;
+    PrincipalHandle principalHandle = mPendingPrincipalHandle;
+    mLastPrincipalHandle = mPendingPrincipalHandle;
+    mPendingPrincipalHandle = PRINCIPAL_HANDLE_NONE;
+    mFrameIDForPendingPrincipalHandle = 0;
+    NS_DispatchToMainThread(NS_NewRunnableFunction([self, principalHandle]() {
+      if (self->mElement) {
+        self->mElement->PrincipalHandleChangedForVideoFrameContainer(self, principalHandle);
+      }
+    }));
+  }
 
   if (aImages.IsEmpty()) {
     mImageContainer->ClearAllImages();
   } else {
     mImageContainer->SetCurrentImages(aImages);
   }
   gfx::IntSize newFrameSize = mImageContainer->GetCurrentSize();
   if (oldFrameSize != newFrameSize) {

--- a/dom/media/VideoFrameContainer.h
+++ b/dom/media/VideoFrameContainer.h
@@ -8,16 +8,17 @@
 #define VIDEOFRAMECONTAINER_H_
 
 #include "mozilla/Mutex.h"
 #include "mozilla/TimeStamp.h"
 #include "gfxPoint.h"
 #include "nsCOMPtr.h"
 #include "nsAutoPtr.h"
 #include "ImageContainer.h"
+#include "MediaSegment.h"
 
 namespace mozilla {
 
 namespace dom {
 class HTMLMediaElement;
 } // namespace dom
 
 /**
@@ -37,16 +38,23 @@ public:
   typedef layers::Image Image;
 
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(VideoFrameContainer)
 
   VideoFrameContainer(dom::HTMLMediaElement* aElement,
                       already_AddRefed<ImageContainer> aContainer);
 
   // Call on any thread
+  // Returns the last principalHandle we notified mElement about.
+  PrincipalHandle GetLastPrincipalHandle();
+  // We will notify mElement that aPrincipalHandle has been applied when all
+  // FrameIDs prior to aFrameID have been flushed out.
+  // aFrameID is ignored if aPrincipalHandle already is our pending principalHandle.
+  void UpdatePrincipalHandleForFrameID(const PrincipalHandle& aPrincipalHandle,
+                                       const ImageContainer::FrameID& aFrameID);
   B2G_ACL_EXPORT void SetCurrentFrame(const gfx::IntSize& aIntrinsicSize, Image* aImage,
                        const TimeStamp& aTargetTime);
   void SetCurrentFrames(const gfx::IntSize& aIntrinsicSize,
                         const nsTArray<ImageContainer::NonOwningImage>& aImages);
   void ClearCurrentFrame(const gfx::IntSize& aIntrinsicSize)
   {
     SetCurrentFrames(aIntrinsicSize, nsTArray<ImageContainer::NonOwningImage>());
   }
@@ -106,13 +114,20 @@ protected:
   // and update the intrinsic size on the element, request a frame reflow and
   // then reset this flag.
   bool mIntrinsicSizeChanged;
   // True when the Image size has changed since the last time Invalidate() was
   // called. When set, the next call to Invalidate() will ensure that the
   // frame is fully invalidated instead of just invalidating for the image change
   // in the ImageLayer.
   bool mImageSizeChanged;
+  // The last PrincipalHandle we notified mElement about.
+  PrincipalHandle mLastPrincipalHandle;
+  // The PrincipalHandle the client has notified us is changing with FrameID
+  // mFrameIDForPendingPrincipalHandle.
+  PrincipalHandle mPendingPrincipalHandle;
+  // The FrameID for which mPendingPrincipal is first valid.
+  ImageContainer::FrameID mFrameIDForPendingPrincipalHandle;
 };
 
 } // namespace mozilla
 
 #endif /* VIDEOFRAMECONTAINER_H_ */