diff --git a/dom/media/mediasession/test/file_active_mediasession_within_page_frame.html b/dom/media/mediasession/test/file_active_mediasession_within_page_frame.html
deleted file mode 100644
index 7d9e6b45e738..000000000000
--- a/dom/media/mediasession/test/file_active_mediasession_within_page_frame.html
+++ /dev/null
@@ -1,16 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-  <head>
-    <title>Test active media session within a page</title>
-    <script src="MediaSessionTestUtils.js"></script>
-  </head>
-<body>
-<script>
-navigator.mediaSession.setActionHandler("play", () => {
-	const w = window.opener || window.parent;
-  w.postMessage("play", "*");
-});
-
-</script>
-</body>
-</html>
diff --git a/dom/media/mediasession/test/file_active_mediasession_within_page_window.html b/dom/media/mediasession/test/file_active_mediasession_within_page_window.html
deleted file mode 100644
index 5d22f1b1fc1f..000000000000
--- a/dom/media/mediasession/test/file_active_mediasession_within_page_window.html
+++ /dev/null
@@ -1,149 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-  <head>
-    <title>Test active media session within a page</title>
-    <script src="/tests/SimpleTest/SimpleTest.js"></script>
-    <script src="MediaSessionTestUtils.js"></script>
-  </head>
-<body>
-<video id="testVideo" src="gizmo.mp4" loop></video>
-<script>
-
-var gActiveSessionShouldBeFrom = "none";
-
-nextWindowMessage().then(
-  async (event) => {
-    const {testCommands} = event.data;
-    // Media session would only become active if there is any media currently
-    // playing. Non-active media session won't receive any actions. Therefore,
-    // we start media playback before testing media session.
-    await startMediaPlayback();
-
-    for (const command of testCommands) {
-      info(`execute command '${command}'`);
-      switch (command) {
-        case gCommands.createMainFrameSession:
-          createSessionInMainFrame();
-          break;
-        case gCommands.createChildFrameSession:
-          await createSessionInChildFrame();
-          break;
-        case gCommands.destroyChildFrameSessions:
-          await destroyAllChildFrames();
-          break;
-        case gCommands.destroyActiveChildFrameSession:
-          await destroyChildFrameWithActiveSession();
-          break;
-        case gCommands.destroyInactiveChildFrameSession:
-          await destroyChildFrameWithInactiveSession();
-          break;
-      };
-    }
-
-    // Finished running all commands, so we can return testing result.
-    await endTestAndReportResult();
-  });
-
-/**
- * The following are helper functions
- */
-async function startMediaPlayback() {
-  info(`wait until media starts playing`);
-  const video = document.getElementById("testVideo");
-  await video.play();
-  // As we can't observe `main-media-controller-playback-changed` notification,
-  // which can only be observed in the chrome process. Therefore, we use a
-  // workaround instead which is to wait for a while to ensure that the
-  // controller has already been created in the chrome process.
-  let timeupdatecount = 0;
-  await new Promise(r => video.ontimeupdate = () => {
-    if (++timeupdatecount == 3) {
-      video.ontimeupdate = null;
-      r();
-    }
-  });
-}
-
-function createSessionInMainFrame() {
-  // Simply referencing media session will create media session.
-  navigator.mediaSession;
-  // Media session created in main frame should always be an active session.
-  gActiveSessionShouldBeFrom = "main-frame";
-}
-
-async function createSessionInChildFrame() {
-  const frame = document.createElement("iframe");
-  frame.src = "file_active_mediasession_within_page_frame.html";
-  frame.id = "child-frame-" + document.getElementsByTagName("iframe").length;
-  document.body.appendChild(frame);
-  info(`wait until ${frame.id } finishing loading`);
-  await new Promise(r => frame.onload = r);
-  // If we haven't created any media session, then this media session should
-  // become an active session. Otherwise, session created in child frame won't
-  // override the current active session and should be inactive session.
-  if (gActiveSessionShouldBeFrom == "none") {
-    gActiveSessionShouldBeFrom = frame.id;
-  }
-}
-
-async function destroyAllChildFrames() {
-  const frames = document.getElementsByTagName("iframe");
-  for (const frame of frames) {
-    document.body.removeChild(frame);
-  }
-}
-
-async function destroyChildFrameWithActiveSession() {
-  const frames = document.getElementsByTagName("iframe");
-  for (const frame of frames) {
-    if (frame.id == gActiveSessionShouldBeFrom) {
-      document.body.removeChild(frame);
-      return;
-    }
-  }
-}
-
-async function destroyChildFrameWithInactiveSession() {
-  const frames = document.getElementsByTagName("iframe");
-  for (const frame of frames) {
-    if (frame.id != gActiveSessionShouldBeFrom) {
-      document.body.removeChild(frame);
-    }
-  }
-}
-
-async function getActiveSessionResult() {
-  // The way we check which session is active is by generating `play` action and
-  // see which session's action hanlder is triggered, because we would only
-  // trigger active session's action handler.
-  const action = "play";
-  info(`we assume active session should be from ${gActiveSessionShouldBeFrom}`);
-  if (gActiveSessionShouldBeFrom == "main-frame") {
-    let promise = new Promise(r => {
-      navigator.mediaSession.setActionHandler(action, () => {
-        info(`active session is from main main-frame`);
-        r();
-      });
-    });
-    SpecialPowers.generateMediaControlKeyTestEvent(action);
-    await promise;
-    return gResults.mainFrameSession;
-  }
-
-  SpecialPowers.generateMediaControlKeyTestEvent(action);
-  const event = await nextWindowMessage();
-  if (gActiveSessionShouldBeFrom == event.source.frameElement.id) {
-    return gResults.childFrameSession;
-  }
-  return gResults.childFrameSessionUpdated;
-}
-
-async function endTestAndReportResult() {
-  const rv = await getActiveSessionResult();
-  const w = window.opener || window.parent;
-  w.postMessage(rv, "*");
-}
-
-</script>
-</body>
-</html>
diff --git a/dom/media/mediasession/test/mochitest.ini b/dom/media/mediasession/test/mochitest.ini
index 4690d6343c38..146f1afea8ff 100644
--- a/dom/media/mediasession/test/mochitest.ini
+++ b/dom/media/mediasession/test/mochitest.ini
@@ -4,12 +4,9 @@ tags = mediasession mediacontrol
 
 support-files =
   ../../test/gizmo.mp4
-  file_active_mediasession_within_page_frame.html
-  file_active_mediasession_within_page_window.html
   file_trigger_actionhanlder_frame.html
   file_trigger_actionhanlder_window.html
   MediaSessionTestUtils.js
 
-[test_active_mediasession_within_page.html]
 [test_setactionhandler.html]
 [test_trigger_actionhanlder.html]
diff --git a/dom/media/mediasession/test/test_active_mediasession_within_page.html b/dom/media/mediasession/test/test_active_mediasession_within_page.html
deleted file mode 100644
index 7936df0e74e1..000000000000
--- a/dom/media/mediasession/test/test_active_mediasession_within_page.html
+++ /dev/null
@@ -1,102 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-  <head>
-    <title>Test active media session within a page</title>
-    <script src="/tests/SimpleTest/SimpleTest.js"></script>
-    <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
-    <script src="MediaSessionTestUtils.js"></script>
-  </head>
-<body>
-<script>
-/**
- * This test is used to check if the active media session is selected correctly
- * when there are multiple media sessions existing within a same page.
- *
- * `testCases` contains all test cases we're going to execute in this test, and
- * each test would be run in a new window. For each test case, we have several
- * test commands which we would send to window, and the test running in window
- * would do different operations depending on what command we send. After the
- * window finishes running all those commands, it would post a message to tell
- * us its testing result, which can represent if where active media session is
- * created and if the active media session has been changed during testing.
- */
-const testCases = [
-  {
-    name: "Session created in main-frame is always active session",
-    testCommands: [
-      gCommands.createMainFrameSession,
-      gCommands.createChildFrameSession,
-    ],
-    expectedResult: gResults.mainFrameSession,
-  },
-  {
-    name: "Session created in child-frame will be overwrited by main-frame's session",
-    testCommands: [
-      gCommands.createChildFrameSession,
-      gCommands.createMainFrameSession,
-    ],
-    expectedResult: gResults.mainFrameSession,
-  },
-  {
-    name: "Session created in child-frame won't be overwrited by other child-frame's session",
-    testCommands: [
-      gCommands.createChildFrameSession,
-      gCommands.createChildFrameSession,
-    ],
-    expectedResult: gResults.childFrameSession,
-  },
-  {
-    name: "Session created in main-frame won't be affected by creation and destruction of child-frame session",
-    testCommands: [
-      gCommands.createMainFrameSession,
-      gCommands.createChildFrameSession,
-      gCommands.destroyChildFrameSessions,
-    ],
-    expectedResult: gResults.mainFrameSession,
-  },
-  {
-    name: "Session created in child-frame won't be affected by creation and destruction of non active child-frame session",
-    testCommands: [
-      gCommands.createChildFrameSession,
-      gCommands.createChildFrameSession,
-      gCommands.destroyInactiveChildFrameSession,
-    ],
-    expectedResult: gResults.childFrameSession,
-  },
-  {
-    name: "Inactive session would become active after active session is destroyed",
-    testCommands: [
-      gCommands.createChildFrameSession,
-      gCommands.createChildFrameSession,
-      gCommands.destroyActiveChildFrameSession,
-    ],
-    expectedResult: gResults.childFrameSessionUpdated,
-  },
-];
-
-SimpleTest.waitForExplicitFinish();
-
-SpecialPowers.pushPrefEnv({"set": [
-  ["dom.media.mediasession.enabled", true],
-  ["media.mediacontrol.testingevents.enabled", true],
-]}, startTest());
-
-async function startTest() {
-  for (const testCase of testCases) {
-    info(`- loading test '${testCase.name}' in a new window -`);
-    const testURL = "file_active_mediasession_within_page_window.html";
-    const testWindow = window.open(testURL, "", "width=500,height=500");
-    await new Promise(r => testWindow.onload = r);
-
-    info("- start running test -");
-    testWindow.postMessage(testCase, window.origin);
-    is((await nextWindowMessage()).data, testCase.expectedResult,
-       `- finished test '${testCase.name}' -`);
-    testWindow.close();
-  }
-  SimpleTest.finish();
-}
-
-</script>
-</body>
-</html>
