1 files changed, 166 insertions, 0 deletions
diff --git a/dom/media/MediaPlaybackDelayPolicy.cpp b/dom/media/MediaPlaybackDelayPolicy.cpp
new file mode 100644
index 0000000000..1ac326db7c
--- /dev/null
+++ b/dom/media/MediaPlaybackDelayPolicy.cpp
@@ -0,0 +1,166 @@
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MediaPlaybackDelayPolicy.h"
+
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/HTMLMediaElement.h"
+#include "mozilla/StaticPrefs_media.h"
+
+namespace mozilla::dom {
+
+using AudibleState = AudioChannelService::AudibleState;
+
+static AudibleState DetermineMediaAudibleState(const HTMLMediaElement* aElement,
+                                               bool aIsAudible) {
+  MOZ_ASSERT(aElement);
+  if (!aElement->HasAudio()) {
+    return AudibleState::eNotAudible;
+  }
+  // `eMaybeAudible` is used to distinguish if the media has audio track or not,
+  // because we would only show the delayed media playback icon for media with
+  // an audio track.
+  return aIsAudible ? AudibleState::eAudible : AudibleState::eMaybeAudible;
+}
+
+ResumeDelayedPlaybackAgent::~ResumeDelayedPlaybackAgent() {
+  if (mDelegate) {
+    mDelegate->Clear();
+    mDelegate = nullptr;
+  }
+}
+
+bool ResumeDelayedPlaybackAgent::InitDelegate(const HTMLMediaElement* aElement,
+                                              bool aIsAudible) {
+  MOZ_ASSERT(!mDelegate, "Delegate has been initialized!");
+  mDelegate = new ResumePlayDelegate();
+  if (!mDelegate->Init(aElement, aIsAudible)) {
+    mDelegate->Clear();
+    mDelegate = nullptr;
+    return false;
+  }
+  return true;
+}
+
+RefPtr<ResumeDelayedPlaybackAgent::ResumePromise>
+ResumeDelayedPlaybackAgent::GetResumePromise() {
+  MOZ_ASSERT(mDelegate);
+  return mDelegate->GetResumePromise();
+}
+
+void ResumeDelayedPlaybackAgent::UpdateAudibleState(
+    const HTMLMediaElement* aElement, bool aIsAudible) {
+  MOZ_ASSERT(aElement);
+  MOZ_ASSERT(mDelegate);
+  mDelegate->UpdateAudibleState(aElement, aIsAudible);
+}
+
+NS_IMPL_ISUPPORTS(ResumeDelayedPlaybackAgent::ResumePlayDelegate,
+                  nsIAudioChannelAgentCallback)
+
+ResumeDelayedPlaybackAgent::ResumePlayDelegate::~ResumePlayDelegate() {
+  MOZ_ASSERT(!mAudioChannelAgent);
+}
+
+bool ResumeDelayedPlaybackAgent::ResumePlayDelegate::Init(
+    const HTMLMediaElement* aElement, bool aIsAudible) {
+  MOZ_ASSERT(aElement);
+  if (!aElement->OwnerDoc()->GetInnerWindow()) {
+    return false;
+  }
+
+  MOZ_ASSERT(!mAudioChannelAgent);
+  mAudioChannelAgent = new AudioChannelAgent();
+  nsresult rv =
+      mAudioChannelAgent->Init(aElement->OwnerDoc()->GetInnerWindow(), this);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    Clear();
+    return false;
+  }
+
+  // Start AudioChannelAgent in order to wait the suspended state change when we
+  // are able to resume delayed playback.
+  AudibleState audibleState = DetermineMediaAudibleState(aElement, aIsAudible);
+  rv = mAudioChannelAgent->NotifyStartedPlaying(audibleState);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    Clear();
+    return false;
+  }
+
+  return true;
+}
+
+void ResumeDelayedPlaybackAgent::ResumePlayDelegate::Clear() {
+  if (mAudioChannelAgent) {
+    mAudioChannelAgent->NotifyStoppedPlaying();
+    mAudioChannelAgent = nullptr;
+  }
+  mPromise.RejectIfExists(true, __func__);
+}
+
+RefPtr<ResumeDelayedPlaybackAgent::ResumePromise>
+ResumeDelayedPlaybackAgent::ResumePlayDelegate::GetResumePromise() {
+  return mPromise.Ensure(__func__);
+}
+
+void ResumeDelayedPlaybackAgent::ResumePlayDelegate::UpdateAudibleState(
+    const HTMLMediaElement* aElement, bool aIsAudible) {
+  MOZ_ASSERT(aElement);
+  // It's possible for the owner of `ResumeDelayedPlaybackAgent` to call
+  // `UpdateAudibleState()` after we resolve the promise and clean resource.
+  if (!mAudioChannelAgent) {
+    return;
+  }
+  AudibleState audibleState = DetermineMediaAudibleState(aElement, aIsAudible);
+  mAudioChannelAgent->NotifyStartedAudible(
+      audibleState,
+      AudioChannelService::AudibleChangedReasons::eDataAudibleChanged);
+}
+
+NS_IMETHODIMP
+ResumeDelayedPlaybackAgent::ResumePlayDelegate::WindowVolumeChanged(
+    float aVolume, bool aMuted) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ResumeDelayedPlaybackAgent::ResumePlayDelegate::WindowAudioCaptureChanged(
+    bool aCapture) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ResumeDelayedPlaybackAgent::ResumePlayDelegate::WindowSuspendChanged(
+    SuspendTypes aSuspend) {
+  if (aSuspend == nsISuspendedTypes::NONE_SUSPENDED) {
+    mPromise.ResolveIfExists(true, __func__);
+    Clear();
+  }
+  return NS_OK;
+}
+
+bool MediaPlaybackDelayPolicy::ShouldDelayPlayback(
+    const HTMLMediaElement* aElement) {
+  MOZ_ASSERT(aElement);
+  if (!StaticPrefs::media_block_autoplay_until_in_foreground()) {
+    return false;
+  }
+
+  const Document* doc = aElement->OwnerDoc();
+  nsPIDOMWindowInner* inner = nsPIDOMWindowInner::From(doc->GetInnerWindow());
+  nsPIDOMWindowOuter* outer = nsPIDOMWindowOuter::GetFromCurrentInner(inner);
+  return outer && outer->ShouldDelayMediaFromStart();
+}
+
+RefPtr<ResumeDelayedPlaybackAgent>
+MediaPlaybackDelayPolicy::CreateResumeDelayedPlaybackAgent(
+    const HTMLMediaElement* aElement, bool aIsAudible) {
+  MOZ_ASSERT(aElement);
+  RefPtr<ResumeDelayedPlaybackAgent> agent = new ResumeDelayedPlaybackAgent();
+  return agent->InitDelegate(aElement, aIsAudible) ? agent : nullptr;
+}
+
+}  // namespace mozilla::dom