Bug 1833266 - part4 : let new created MDSM have the same status with …

…the old one. r=jolin

Some attributes of media decoder can be mirrored to MDSM automatically
by state mirroring.

But seeking and playback rate change needs to be performed manually in
order to let the new created MDSM look like the old one.

Differential Revision: https://phabricator.services.mozilla.com/D178127

dom/media/MediaDecoder.cpp

@@ -470,7 +470,12 @@ void MediaDecoder::OnPlaybackErrorEvent(const MediaResult& aError) {
     LOG("Failed to create a new state machine!");
   }
 
-  // TODO : need to make the new MDSM have the same status as the previous one
+  // Some attributes might have been set on the destroyed state machine, and
+  // won't be reflected on the new MDSM by the state mirroring. We need to
+  // update them manually later, after MDSM finished reading the
+  // metadata because the MDSM might not be ready to perform the operations yet.
+  mPendingStatusUpdateForNewlyCreatedStateMachine = true;
+
   discardStateMachine->BeginShutdown()->Then(
       AbstractThread::MainThread(), __func__, [discardStateMachine] {});
 #endif
@@ -779,6 +784,18 @@ void MediaDecoder::MetadataLoaded(
   // the media element has the latest dimensions.
   Invalidate();
 
+#ifdef MOZ_WMF_MEDIA_ENGINE
+  if (mPendingStatusUpdateForNewlyCreatedStateMachine) {
+    mPendingStatusUpdateForNewlyCreatedStateMachine = false;
+    if (mLogicalPosition != 0) {
+      Seek(mLogicalPosition, SeekTarget::Accurate);
+    }
+    if (mPlaybackRate != 0 && mPlaybackRate != 1.0) {
+      mDecoderStateMachine->DispatchSetPlaybackRate(mPlaybackRate);
+    }
+  }
+#endif
+
   EnsureTelemetryReported();
 }
 

dom/media/MediaDecoder.h

@@ -818,6 +818,12 @@ class MediaDecoder : public DecoderDoctorLifeLogger<MediaDecoder> {
   bool mCanPlayThrough = false;
 
   UniquePtr<TelemetryProbesReporter> mTelemetryProbesReporter;
+
+#  ifdef MOZ_WMF_MEDIA_ENGINE
+  // True when we need to update the newly created MDSM's status to make it
+  // consistent with the previous destroyed one.
+  bool mPendingStatusUpdateForNewlyCreatedStateMachine = false;
+#  endif
 };
 
 typedef MozPromise<mozilla::dom::MediaMemoryInfo, nsresult, true>