1 files changed, 134 insertions, 0 deletions
diff --git a/dom/media/mediacontrol/AudioFocusManager.cpp b/dom/media/mediacontrol/AudioFocusManager.cpp
new file mode 100644
index 0000000000..24ac7374d4
--- /dev/null
+++ b/dom/media/mediacontrol/AudioFocusManager.cpp
@@ -0,0 +1,134 @@
+/* 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 "AudioFocusManager.h"
+
+#include "MediaController.h"
+#include "MediaControlUtils.h"
+#include "MediaControlService.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "mozilla/Logging.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/Telemetry.h"
+#include "nsThreadUtils.h"
+
+#undef LOG
+#define LOG(msg, ...)                        \
+  MOZ_LOG(gMediaControlLog, LogLevel::Debug, \
+          ("AudioFocusManager=%p, " msg, this, ##__VA_ARGS__))
+
+namespace mozilla::dom {
+
+void AudioFocusManager::RequestAudioFocus(IMediaController* aController) {
+  MOZ_ASSERT(aController);
+  if (mOwningFocusControllers.Contains(aController)) {
+    return;
+  }
+  const bool hasManagedAudioFocus = ClearFocusControllersIfNeeded();
+  LOG("Controller %" PRId64 " grants audio focus", aController->Id());
+  mOwningFocusControllers.AppendElement(aController);
+  if (hasManagedAudioFocus) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_TABS_AUDIO_COMPETITION::ManagedFocusByGecko);
+  } else if (GetAudioFocusNums() == 1) {
+    // Only one audible tab is playing within gecko.
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_TABS_AUDIO_COMPETITION::None);
+  } else {
+    // Multiple audible tabs are playing at the same time within gecko.
+    CreateTimerForUpdatingTelemetry();
+  }
+}
+
+void AudioFocusManager::RevokeAudioFocus(IMediaController* aController) {
+  MOZ_ASSERT(aController);
+  if (!mOwningFocusControllers.Contains(aController)) {
+    return;
+  }
+  LOG("Controller %" PRId64 " loses audio focus", aController->Id());
+  mOwningFocusControllers.RemoveElement(aController);
+}
+
+bool AudioFocusManager::ClearFocusControllersIfNeeded() {
+  // Enable audio focus management will start the audio competition which is
+  // only allowing one controller playing at a time.
+  if (!StaticPrefs::media_audioFocus_management()) {
+    return false;
+  }
+
+  bool hasStoppedAnyController = false;
+  for (auto& controller : mOwningFocusControllers) {
+    LOG("Controller %" PRId64 " loses audio focus in audio competitition",
+        controller->Id());
+    hasStoppedAnyController = true;
+    controller->Stop();
+  }
+  mOwningFocusControllers.Clear();
+  return hasStoppedAnyController;
+}
+
+uint32_t AudioFocusManager::GetAudioFocusNums() const {
+  return mOwningFocusControllers.Length();
+}
+
+void AudioFocusManager::CreateTimerForUpdatingTelemetry() {
+  MOZ_ASSERT(NS_IsMainThread());
+  // Already create the timer.
+  if (mTelemetryTimer) {
+    return;
+  }
+
+  const uint32_t focusNum = GetAudioFocusNums();
+  MOZ_ASSERT(focusNum > 1);
+
+  RefPtr<MediaControlService> service = MediaControlService::GetService();
+  MOZ_ASSERT(service);
+  const uint32_t activeControllerNum = service->GetActiveControllersNum();
+
+  // It takes time if users want to manually manage the audio competition by
+  // pausing one of playing tabs. So we will check the status after a short
+  // while to see if users handle the audio competition, or simply ignore it.
+  nsCOMPtr<nsIRunnable> task = NS_NewRunnableFunction(
+      "AudioFocusManager::RequestAudioFocus",
+      [focusNum, activeControllerNum]() {
+        if (RefPtr<MediaControlService> service =
+                MediaControlService::GetService()) {
+          service->GetAudioFocusManager().UpdateTelemetryDataFromTimer(
+              focusNum, activeControllerNum);
+        }
+      });
+  mTelemetryTimer =
+      SimpleTimer::Create(task, 4000, GetMainThreadSerialEventTarget());
+}
+
+void AudioFocusManager::UpdateTelemetryDataFromTimer(
+    uint32_t aPrevFocusNum, uint64_t aPrevActiveControllerNum) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mTelemetryTimer);
+  // Users pause or mute tabs which decreases the amount of audible playing
+  // tabs, which should not affect the total controller amount.
+  if (GetAudioFocusNums() < aPrevFocusNum) {
+    // If active controller amount is not equal, that means controllers got
+    // deactivated by other reasons, such as reaching to the end, which are not
+    // the situation we would like to accumulate for telemetry.
+    if (MediaControlService::GetService()->GetActiveControllersNum() ==
+        aPrevActiveControllerNum) {
+      AccumulateCategorical(mozilla::Telemetry::LABELS_TABS_AUDIO_COMPETITION::
+                                ManagedFocusByUser);
+    }
+  } else {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_TABS_AUDIO_COMPETITION::Ignored);
+  }
+  mTelemetryTimer = nullptr;
+}
+
+AudioFocusManager::~AudioFocusManager() {
+  if (mTelemetryTimer) {
+    mTelemetryTimer->Cancel();
+    mTelemetryTimer = nullptr;
+  }
+}
+
+}  // namespace mozilla::dom