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diff --git a/dom/media/mediacontrol/MediaPlaybackStatus.h b/dom/media/mediacontrol/MediaPlaybackStatus.h
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+/* 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/. */
+
+#ifndef DOM_MEDIA_MEDIACONTROL_MEDIAPLAYBACKSTATUS_H_
+#define DOM_MEDIA_MEDIACONTROL_MEDIAPLAYBACKSTATUS_H_
+
+#include "mozilla/Maybe.h"
+#include "mozilla/RefPtr.h"
+#include "nsISupportsImpl.h"
+#include "nsTArray.h"
+#include "nsTHashMap.h"
+
+namespace mozilla::dom {
+
+/**
+ * This enum is used to update controlled media state to the media controller in
+ * the chrome process.
+ * `eStarted`: media has successfully registered to the content media controller
+ * `ePlayed` : media has started playing
+ * `ePaused` : media has paused playing, but still can be resumed by content
+ *             media controller
+ * `eStopped`: media has unregistered from the content media controller, we can
+ *             not control it anymore
+ */
+enum class MediaPlaybackState : uint32_t {
+  eStarted,
+  ePlayed,
+  ePaused,
+  eStopped,
+};
+
+/**
+ * This enum is used to update controlled media audible audible state to the
+ * media controller in the chrome process.
+ */
+enum class MediaAudibleState : bool {
+  eInaudible = false,
+  eAudible = true,
+};
+
+/**
+ * MediaPlaybackStatus is an internal module for the media controller, it
+ * represents a tab's media related status, such like "does the tab contain any
+ * controlled media? is the tab playing? is the tab audible?".
+ *
+ * The reason we need this class is that we would like to encapsulate the
+ * details of determining the tab's media status. A tab can contains multiple
+ * browsing contexts, and each browsing context can have different media status.
+ * The final media status would be decided by checking all those context status.
+ *
+ * Use `UpdateMediaXXXState()` to update controlled media status, and use
+ * `IsXXX()` methods to acquire the playback status of the tab.
+ *
+ * As we know each context's audible state, we can decide which context should
+ * owns the audio focus when multiple contexts are all playing audible media at
+ * the same time. In that cases, the latest context that plays media would own
+ * the audio focus. When the context owning the audio focus is destroyed, we
+ * would see if there is another other context still playing audible media, and
+ * switch the audio focus to another context.
+ */
+class MediaPlaybackStatus final {
+ public:
+  void UpdateMediaPlaybackState(uint64_t aContextId, MediaPlaybackState aState);
+  void UpdateMediaAudibleState(uint64_t aContextId, MediaAudibleState aState);
+
+  bool IsPlaying() const;
+  bool IsAudible() const;
+  bool IsAnyMediaBeingControlled() const;
+
+  Maybe<uint64_t> GetAudioFocusOwnerContextId() const;
+
+ private:
+  /**
+   * This internal class stores detailed media status of controlled media for
+   * a browsing context.
+   */
+  class ContextMediaInfo final {
+   public:
+    explicit ContextMediaInfo(uint64_t aContextId) : mContextId(aContextId) {}
+    ~ContextMediaInfo() = default;
+
+    void IncreaseControlledMediaNum() {
+      MOZ_DIAGNOSTIC_ASSERT(mControlledMediaNum < UINT_MAX);
+      mControlledMediaNum++;
+    }
+    void DecreaseControlledMediaNum() {
+      MOZ_DIAGNOSTIC_ASSERT(mControlledMediaNum > 0);
+      mControlledMediaNum--;
+    }
+    void IncreasePlayingMediaNum() {
+      MOZ_DIAGNOSTIC_ASSERT(mPlayingMediaNum < mControlledMediaNum);
+      mPlayingMediaNum++;
+    }
+    void DecreasePlayingMediaNum() {
+      MOZ_DIAGNOSTIC_ASSERT(mPlayingMediaNum > 0);
+      mPlayingMediaNum--;
+    }
+    void IncreaseAudibleMediaNum() {
+      MOZ_DIAGNOSTIC_ASSERT(mAudibleMediaNum < mPlayingMediaNum);
+      mAudibleMediaNum++;
+    }
+    void DecreaseAudibleMediaNum() {
+      MOZ_DIAGNOSTIC_ASSERT(mAudibleMediaNum > 0);
+      mAudibleMediaNum--;
+    }
+    bool IsPlaying() const { return mPlayingMediaNum > 0; }
+    bool IsAudible() const { return mAudibleMediaNum > 0; }
+    bool IsAnyMediaBeingControlled() const { return mControlledMediaNum > 0; }
+    uint64_t Id() const { return mContextId; }
+
+   private:
+    /**
+     * The possible value for those three numbers should follow this rule,
+     * mControlledMediaNum >= mPlayingMediaNum >= mAudibleMediaNum
+     */
+    uint32_t mControlledMediaNum = 0;
+    uint32_t mAudibleMediaNum = 0;
+    uint32_t mPlayingMediaNum = 0;
+    uint64_t mContextId = 0;
+  };
+
+  ContextMediaInfo& GetNotNullContextInfo(uint64_t aContextId);
+  void DestroyContextInfo(uint64_t aContextId);
+
+  void ChooseNewContextToOwnAudioFocus();
+  void SetOwningAudioFocusContextId(Maybe<uint64_t>&& aContextId);
+  bool IsContextOwningAudioFocus(uint64_t aContextId) const;
+  bool ShouldRequestAudioFocusForInfo(const ContextMediaInfo& aInfo) const;
+  bool ShouldAbandonAudioFocusForInfo(const ContextMediaInfo& aInfo) const;
+
+  // This contains all the media status of browsing contexts within a tab.
+  nsTHashMap<uint64_t, UniquePtr<ContextMediaInfo>> mContextInfoMap;
+  Maybe<uint64_t> mOwningAudioFocusContextId;
+};
+
+}  // namespace mozilla::dom
+
+#endif  //  DOM_MEDIA_MEDIACONTROL_MEDIAPLAYBACKSTATUS_H_