Bug 1521964 - Add privileged HTMLVideoElement.cloneElementVisually WebIDL method. r=jya,Ehsan,smaug

Differential Revision: https://phabricator.services.mozilla.com/D20023

--HG--
extra : moz-landing-system : lando

dom/html/HTMLMediaElement.cpp

@@ -2056,6 +2056,7 @@ void HTMLMediaElement::ResetState() {
 
 void HTMLMediaElement::SelectResourceWrapper() {
   SelectResource();
+  MaybeBeginCloningVisually();
   mIsRunningSelectResource = false;
   mHaveQueuedSelectResource = false;
   mIsDoingExplicitLoad = false;
@@ -2183,6 +2184,7 @@ void HTMLMediaElement::NotifyMediaTrackEnabled(MediaTrack* aTrack) {
       VideoFrameContainer* container = GetVideoFrameContainer();
       if (mSrcStreamIsPlaying && container) {
         mSelectedVideoStreamTrack->AddVideoOutput(container);
+        MaybeBeginCloningVisually();
       }
       HTMLVideoElement* self = static_cast<HTMLVideoElement*>(this);
       if (self->VideoWidth() <= 1 && self->VideoHeight() <= 1) {
@@ -4591,6 +4593,8 @@ nsresult HTMLMediaElement::FinishDecoderSetup(MediaDecoder* aDecoder) {
     }
   }
 
+  MaybeBeginCloningVisually();
+
   return NS_OK;
 }
 
@@ -4681,6 +4685,7 @@ void HTMLMediaElement::UpdateSrcMediaStreamPlaying(uint32_t aFlags) {
     VideoFrameContainer* container = GetVideoFrameContainer();
     if (mSelectedVideoStreamTrack && container) {
       mSelectedVideoStreamTrack->AddVideoOutput(container);
+      MaybeBeginCloningVisually();
     }
 
     SetCapturedOutputStreamsEnabled(true);  // Unmute

dom/html/HTMLMediaElement.h

@@ -298,7 +298,7 @@ class HTMLMediaElement : public nsGenericHTMLElement,
 
   // Update the visual size of the media. Called from the decoder on the
   // main thread when/if the size changes.
-  void UpdateMediaSize(const nsIntSize& aSize);
+  virtual void UpdateMediaSize(const nsIntSize& aSize);
   // Like UpdateMediaSize, but only updates the size if no size has yet
   // been set.
   void UpdateInitialMediaSize(const nsIntSize& aSize);
@@ -1720,6 +1720,8 @@ class HTMLMediaElement : public nsGenericHTMLElement,
 
   void UpdateHadAudibleAutoplayState();
 
+  virtual void MaybeBeginCloningVisually(){};
+
   /**
    * This function is called by AfterSetAttr and OnAttrSetButNotChanged.
    * It will not be called if the value is being unset.

dom/html/HTMLVideoElement.cpp

@@ -25,12 +25,14 @@
 #include "FrameStatistics.h"
 #include "MediaError.h"
 #include "MediaDecoder.h"
+#include "MediaDecoderStateMachine.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/dom/WakeLock.h"
 #include "mozilla/dom/power/PowerManagerService.h"
 #include "mozilla/dom/Performance.h"
 #include "mozilla/dom/TimeRanges.h"
 #include "mozilla/dom/VideoPlaybackQuality.h"
+#include "mozilla/dom/VideoStreamTrack.h"
 
 #include <algorithm>
 #include <limits>
@@ -66,8 +68,22 @@ nsresult HTMLVideoElement::Clone(mozilla::dom::NodeInfo* aNodeInfo,
 NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(HTMLVideoElement,
                                                HTMLMediaElement)
 
-NS_IMPL_CYCLE_COLLECTION_INHERITED(HTMLVideoElement, HTMLMediaElement,
-                                   mVisualCloneTarget, mVisualCloneSource)
+NS_IMPL_CYCLE_COLLECTION_CLASS(HTMLVideoElement)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLVideoElement,
+                                                HTMLMediaElement)
+  if (tmp->mVisualCloneTarget) {
+    tmp->EndCloningVisually();
+  }
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mVisualCloneTarget)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mVisualCloneSource)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(HTMLVideoElement,
+                                                  HTMLMediaElement)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mVisualCloneTarget)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mVisualCloneSource)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 HTMLVideoElement::HTMLVideoElement(already_AddRefed<NodeInfo>&& aNodeInfo)
     : HTMLMediaElement(std::move(aNodeInfo)), mIsOrientationLocked(false) {
@@ -78,6 +94,15 @@ HTMLVideoElement::~HTMLVideoElement() {
   DecoderDoctorLogger::LogDestruction(this);
 }
 
+void HTMLVideoElement::UpdateMediaSize(const nsIntSize& aSize) {
+  HTMLMediaElement::UpdateMediaSize(aSize);
+  // If we have a clone target, we should update its size as well.
+  if (mVisualCloneTarget) {
+    Maybe<nsIntSize> newSize = Some(aSize);
+    mVisualCloneTarget->Invalidate(true, newSize, true);
+  }
+}
+
 nsresult HTMLVideoElement::GetVideoSize(nsIntSize* size) {
   if (!mMediaInfo.HasVideo()) {
     return NS_ERROR_FAILURE;
@@ -139,6 +164,18 @@ nsMapRuleToAttributesFunc HTMLVideoElement::GetAttributeMappingFunction()
   return &MapAttributesIntoRule;
 }
 
+void HTMLVideoElement::UnbindFromTree(bool aDeep, bool aNullParent) {
+  if (mVisualCloneSource) {
+    mVisualCloneSource->EndCloningVisually();
+    SetVisualCloneSource(nullptr);
+  } else if (mVisualCloneTarget) {
+    mVisualCloneTarget->SetVisualCloneSource(nullptr);
+    EndCloningVisually();
+  }
+
+  HTMLMediaElement::UnbindFromTree(aDeep, aNullParent);
+}
+
 nsresult HTMLVideoElement::SetAcceptHeader(nsIHttpChannel* aChannel) {
   nsAutoCString value(
       "video/webm,"
@@ -396,5 +433,73 @@ double HTMLVideoElement::TotalPlayTime() const {
   return total;
 }
 
+void HTMLVideoElement::CloneElementVisually(HTMLVideoElement& aTargetVideo,
+                                            ErrorResult& rv) {
+  MOZ_ASSERT(!mUnboundFromTree,
+             "Can't clone a video that's not bound to a DOM tree.");
+  MOZ_ASSERT(!aTargetVideo.mUnboundFromTree,
+             "Can't clone to a video that's not bound to a DOM tree.");
+  if (mUnboundFromTree || aTargetVideo.mUnboundFromTree) {
+    rv.Throw(NS_ERROR_UNEXPECTED);
+    return;
+  }
+
+  if (!SetVisualCloneTarget(&aTargetVideo)) {
+    rv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  if (!aTargetVideo.SetVisualCloneSource(this)) {
+    mVisualCloneTarget = nullptr;
+    rv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  aTargetVideo.SetMediaInfo(mMediaInfo);
+
+  MaybeBeginCloningVisually();
+}
+
+void HTMLVideoElement::MaybeBeginCloningVisually() {
+  if (!mVisualCloneTarget) {
+    return;
+  }
+
+  if (mDecoder) {
+    MediaDecoderStateMachine* mdsm = mDecoder->GetStateMachine();
+    VideoFrameContainer* container =
+        mVisualCloneTarget->GetVideoFrameContainer();
+    if (mdsm && container) {
+      mdsm->SetSecondaryVideoContainer(container);
+    }
+  } else if (mSrcStream) {
+    VideoFrameContainer* container =
+        mVisualCloneTarget->GetVideoFrameContainer();
+    if (container && mSelectedVideoStreamTrack) {
+      mSelectedVideoStreamTrack->AddVideoOutput(container);
+    }
+  }
+}
+
+void HTMLVideoElement::EndCloningVisually() {
+  MOZ_ASSERT(mVisualCloneTarget);
+
+  if (mDecoder) {
+    MediaDecoderStateMachine* mdsm = mDecoder->GetStateMachine();
+    if (mdsm) {
+      mdsm->SetSecondaryVideoContainer(nullptr);
+    }
+  } else if (mSrcStream) {
+    VideoFrameContainer* container =
+        mVisualCloneTarget->GetVideoFrameContainer();
+    if (container && mVisualCloneTarget->mSelectedVideoStreamTrack) {
+      mVisualCloneTarget->mSelectedVideoStreamTrack->RemoveVideoOutput(
+          container);
+    }
+  }
+
+  mVisualCloneTarget = nullptr;
+}
+
 }  // namespace dom
 }  // namespace mozilla

dom/html/HTMLVideoElement.h

@@ -48,10 +48,15 @@ class HTMLVideoElement final : public HTMLMediaElement {
 
   virtual nsresult Clone(NodeInfo*, nsINode** aResult) const override;
 
+  virtual void UnbindFromTree(bool aDeep = true,
+                              bool aNullParent = true) override;
+
   // Set size with the current video frame's height and width.
   // If there is no video frame, returns NS_ERROR_FAILURE.
   nsresult GetVideoSize(nsIntSize* size);
 
+  virtual void UpdateMediaSize(const nsIntSize& aSize) override;
+
   virtual nsresult SetAcceptHeader(nsIHttpChannel* aChannel) override;
 
   // Element
@@ -129,6 +134,8 @@ class HTMLVideoElement final : public HTMLMediaElement {
 
   void SetMozIsOrientationLocked(bool aLock) { mIsOrientationLocked = aLock; }
 
+  void CloneElementVisually(HTMLVideoElement& aTarget, ErrorResult& rv);
+
  protected:
   virtual ~HTMLVideoElement();
 
@@ -177,6 +184,9 @@ class HTMLVideoElement final : public HTMLMediaElement {
 
   static bool IsVideoStatsEnabled();
   double TotalPlayTime() const;
+
+  virtual void MaybeBeginCloningVisually() override;
+  void EndCloningVisually();
 };
 
 }  // namespace dom

dom/webidl/HTMLVideoElement.webidl

@@ -53,6 +53,12 @@ partial interface HTMLVideoElement {
   // True if screen orientation is locked by video controls.
   [Pref="media.videocontrols.lock-video-orientation", Func="IsChromeOrXBLOrUAWidget"]
     attribute boolean mozIsOrientationLocked;
+
+  // Clones the frames playing in this <video> to the target. Cloning
+  // when either node is removed from their DOM trees. Throws if one or
+  // both <video> elements are not attached to a DOM tree.
+  [Throws, Func="IsChromeOrXBLOrUAWidget"]
+    void cloneElementVisually(HTMLVideoElement target);
 };
 
 // https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html#idl-def-HTMLVideoElement