Add pop-out player for audio/video in web UI (#14870)

Fix #11160

app/javascript/mastodon/actions/picture_in_picture.js

@@ -0,0 +1,38 @@
+// @ts-check
+
+export const PICTURE_IN_PICTURE_DEPLOY = 'PICTURE_IN_PICTURE_DEPLOY';
+export const PICTURE_IN_PICTURE_REMOVE = 'PICTURE_IN_PICTURE_REMOVE';
+
+/**
+ * @typedef MediaProps
+ * @property {string} src
+ * @property {boolean} muted
+ * @property {number} volume
+ * @property {number} currentTime
+ * @property {string} poster
+ * @property {string} backgroundColor
+ * @property {string} foregroundColor
+ * @property {string} accentColor
+ */
+
+/**
+ * @param {string} statusId
+ * @param {string} accountId
+ * @param {string} playerType
+ * @param {MediaProps} props
+ * @return {object}
+ */
+export const deployPictureInPicture = (statusId, accountId, playerType, props) => ({
+  type: PICTURE_IN_PICTURE_DEPLOY,
+  statusId,
+  accountId,
+  playerType,
+  props,
+});
+
+/*
+ * @return {object}
+ */
+export const removePictureInPicture = () => ({
+  type: PICTURE_IN_PICTURE_REMOVE,
+});