1 files changed, 64 insertions, 0 deletions
diff --git a/dom/media/mediacontrol/MediaPlaybackStatus.cpp b/dom/media/mediacontrol/MediaPlaybackStatus.cpp
index 80dedf8599..434d6dbd7e 100644
--- a/dom/media/mediacontrol/MediaPlaybackStatus.cpp
+++ b/dom/media/mediacontrol/MediaPlaybackStatus.cpp
@@ -71,6 +71,23 @@ void MediaPlaybackStatus::UpdateMediaAudibleState(uint64_t aContextId,
   }
 }
 
+void MediaPlaybackStatus::UpdateGuessedPositionState(
+    uint64_t aContextId, const nsID& aElementId,
+    const Maybe<PositionState>& aState) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (aState) {
+    LOG("Update guessed position state for context %" PRIu64
+        " element %s (duration=%f, playbackRate=%f, position=%f)",
+        aContextId, aElementId.ToString().get(), aState->mDuration,
+        aState->mPlaybackRate, aState->mLastReportedPlaybackPosition);
+  } else {
+    LOG("Clear guessed position state for context %" PRIu64 " element %s",
+        aContextId, aElementId.ToString().get());
+  }
+  ContextMediaInfo& info = GetNotNullContextInfo(aContextId);
+  info.UpdateGuessedPositionState(aElementId, aState);
+}
+
 bool MediaPlaybackStatus::IsPlaying() const {
   MOZ_ASSERT(NS_IsMainThread());
   return std::any_of(mContextInfoMap.Values().cbegin(),
@@ -92,6 +109,35 @@ bool MediaPlaybackStatus::IsAnyMediaBeingControlled() const {
       [](const auto& info) { return info->IsAnyMediaBeingControlled(); });
 }
 
+Maybe<PositionState> MediaPlaybackStatus::GuessedMediaPositionState(
+    Maybe<uint64_t> aPreferredContextId) const {
+  auto contextId = aPreferredContextId;
+  if (!contextId) {
+    contextId = mOwningAudioFocusContextId;
+  }
+
+  // either the preferred or focused context
+  if (contextId) {
+    auto entry = mContextInfoMap.Lookup(*contextId);
+    if (!entry) {
+      return Nothing();
+    }
+    LOG("Using guessed position state from preferred/focused BC %" PRId64,
+        *contextId);
+    return entry.Data()->GuessedPositionState();
+  }
+
+  // look for the first position state
+  for (const auto& context : mContextInfoMap.Values()) {
+    auto state = context->GuessedPositionState();
+    if (state) {
+      LOG("Using guessed position state from BC %" PRId64, context->Id());
+      return state;
+    }
+  }
+  return Nothing();
+}
+
 MediaPlaybackStatus::ContextMediaInfo&
 MediaPlaybackStatus::GetNotNullContextInfo(uint64_t aContextId) {
   MOZ_ASSERT(NS_IsMainThread());
@@ -139,4 +185,22 @@ bool MediaPlaybackStatus::IsContextOwningAudioFocus(uint64_t aContextId) const {
                                     : false;
 }
 
+Maybe<PositionState>
+MediaPlaybackStatus::ContextMediaInfo::GuessedPositionState() const {
+  if (mGuessedPositionStateMap.Count() != 1) {
+    LOG("Count is %d", mGuessedPositionStateMap.Count());
+    return Nothing();
+  }
+  return Some(mGuessedPositionStateMap.begin()->GetData());
+}
+
+void MediaPlaybackStatus::ContextMediaInfo::UpdateGuessedPositionState(
+    const nsID& aElementId, const Maybe<PositionState>& aState) {
+  if (aState) {
+    mGuessedPositionStateMap.InsertOrUpdate(aElementId, *aState);
+  } else {
+    mGuessedPositionStateMap.Remove(aElementId);
+  }
+}
+
 }  // namespace mozilla::dom