--- a/toolkit/content/tests/browser/browser_audioCompeting.js
+++ b/toolkit/content/tests/browser/browser_audioCompeting.js
@@ -1,24 +1,10 @@
 const PAGE = "https://example.com/browser/toolkit/content/tests/browser/file_multipleAudio.html";
 
-function* wait_for_tab_playing_event(tab, expectPlaying) {
-  if (tab.soundPlaying == expectPlaying) {
-    ok(true, "The tab should " + (expectPlaying ? "" : "not ") + "be playing");
-  } else {
-    yield BrowserTestUtils.waitForEvent(tab, "TabAttrModified", false, (event) => {
-      if (event.detail.changed.indexOf("soundplaying") >= 0) {
-        is(tab.soundPlaying, expectPlaying, "The tab should " + (expectPlaying ? "" : "not ") + "be playing");
-        return true;
-      }
-      return false;
-    });
-  }
-}
-
 function play_audio_from_invisible_tab() {
   return new Promise(resolve => {
     var autoPlay = content.document.getElementById("autoplay");
     if (!autoPlay) {
       ok(false, "Can't get the audio element!");
     }
 
     is(autoPlay.paused, true, "Audio in tab 1 was paused by audio competing.");
@@ -68,23 +54,23 @@ add_task(function* setup_test_preference
     ]});
 });
 
 add_task(function* cross_tabs_audio_competing() {
   info("- open tab 1 in foreground -");
   let tab1 = yield BrowserTestUtils.openNewForegroundTab(window.gBrowser,
                                                          "about:blank");
   tab1.linkedBrowser.loadURI(PAGE);
-  yield wait_for_tab_playing_event(tab1, true);
+  yield waitForTabPlayingEvent(tab1, true);
 
   info("- open tab 2 in foreground -");
   let tab2 = yield BrowserTestUtils.openNewForegroundTab(window.gBrowser,
                                                         "about:blank");
   tab2.linkedBrowser.loadURI(PAGE);
-  yield wait_for_tab_playing_event(tab1, false);
+  yield waitForTabPlayingEvent(tab1, false);
 
   info("- open tab 3 in foreground -");
   let tab3 = yield BrowserTestUtils.openNewForegroundTab(window.gBrowser,
                                                          "about:blank");
   yield ContentTask.spawn(tab2.linkedBrowser, null,
                           audio_should_keep_playing_even_go_to_background);
 
   info("- play audio from background tab 1 -");
@@ -97,17 +83,17 @@ add_task(function* cross_tabs_audio_comp
   yield BrowserTestUtils.removeTab(tab3);
 });
 
 add_task(function* within_one_tab_audio_competing() {
   info("- open tab and play audio1 -");
   let tab = yield BrowserTestUtils.openNewForegroundTab(window.gBrowser,
                                                         "about:blank");
   tab.linkedBrowser.loadURI(PAGE);
-  yield wait_for_tab_playing_event(tab, true);
+  yield waitForTabPlayingEvent(tab, true);
 
   info("- play audio2 in the same tab -");
   yield ContentTask.spawn(tab.linkedBrowser, null,
                           play_non_autoplay_audio);
 
   info("- remove tab -");
   yield BrowserTestUtils.removeTab(tab);
 });

--- a/toolkit/content/tests/browser/browser_block_autoplay_media.js
+++ b/toolkit/content/tests/browser/browser_block_autoplay_media.js
@@ -2,30 +2,16 @@ const PAGE = "https://example.com/browse
 
 var SuspendedType = {
   NONE_SUSPENDED             : 0,
   SUSPENDED_PAUSE            : 1,
   SUSPENDED_BLOCK            : 2,
   SUSPENDED_PAUSE_DISPOSABLE : 3
 };
 
-function* wait_for_tab_playing_event(tab, expectPlaying) {
-  if (tab.soundPlaying == expectPlaying) {
-    ok(true, "The tab should " + (expectPlaying ? "" : "not ") + "be playing");
-  } else {
-    yield BrowserTestUtils.waitForEvent(tab, "TabAttrModified", false, (event) => {
-      if (event.detail.changed.indexOf("soundplaying") >= 0) {
-        is(tab.soundPlaying, expectPlaying, "The tab should " + (expectPlaying ? "" : "not ") + "be playing");
-        return true;
-      }
-      return false;
-    });
-  }
-}
-
 function check_audio_suspended(suspendedType) {
   var autoPlay = content.document.getElementById("autoplay");
   if (!autoPlay) {
     ok(false, "Can't get the audio element!");
   }
 
   is(autoPlay.computedSuspended, suspendedType,
      "The suspeded state of autoplay audio is correct.");
@@ -56,30 +42,30 @@ add_task(function* block_autoplay_media(
   info("- should block autoplay for non-visited tab2 -");
   yield ContentTask.spawn(tab2.linkedBrowser, SuspendedType.SUSPENDED_BLOCK,
                           check_audio_suspended);
 
   info("- select tab1 as foreground tab -");
   yield BrowserTestUtils.switchTab(window.gBrowser, tab1);
 
   info("- media should be unblocked because the tab was visited -");
-  yield wait_for_tab_playing_event(tab1, true);
+  yield waitForTabPlayingEvent(tab1, true);
   yield ContentTask.spawn(tab1.linkedBrowser, SuspendedType.NONE_SUSPENDED,
                           check_audio_suspended);
 
   info("- open another new foreground tab3 -");
   let tab3 = yield BrowserTestUtils.openNewForegroundTab(window.gBrowser,
                                                          "about:blank");
   info("- should still play media from tab1 -");
-  yield wait_for_tab_playing_event(tab1, true);
+  yield waitForTabPlayingEvent(tab1, true);
   yield ContentTask.spawn(tab1.linkedBrowser, SuspendedType.NONE_SUSPENDED,
                           check_audio_suspended);
 
   info("- should still block media from tab2 -");
-  yield wait_for_tab_playing_event(tab2, false);
+  yield waitForTabPlayingEvent(tab2, false);
   yield ContentTask.spawn(tab2.linkedBrowser, SuspendedType.SUSPENDED_BLOCK,
                           check_audio_suspended);
 
   info("- remove tabs -");
   yield BrowserTestUtils.removeTab(tab1);
   yield BrowserTestUtils.removeTab(tab2);
   yield BrowserTestUtils.removeTab(tab3);
 });

--- a/toolkit/content/tests/browser/browser_block_silentAudioTrack_media.js
+++ b/toolkit/content/tests/browser/browser_block_silentAudioTrack_media.js
@@ -2,31 +2,16 @@ const PAGE = "https://example.com/browse
 
 var SuspendedType = {
   NONE_SUSPENDED             : 0,
   SUSPENDED_PAUSE            : 1,
   SUSPENDED_BLOCK            : 2,
   SUSPENDED_PAUSE_DISPOSABLE : 3
 };
 
-function* wait_for_tab_playing_event(tab, expectPlaying) {
-  if (tab.soundPlaying == expectPlaying) {
-    ok(true, "The tab should " + (expectPlaying ? "" : "not ") + "be playing");
-  } else {
-    info("Playing state doens't match, wait for attributes changes.");
-    yield BrowserTestUtils.waitForEvent(tab, "TabAttrModified", false, (event) => {
-      if (event.detail.changed.indexOf("soundplaying") >= 0) {
-        is(tab.soundPlaying, expectPlaying, "The tab should " + (expectPlaying ? "" : "not ") + "be playing");
-        return true;
-      }
-      return false;
-    });
-  }
-}
-
 function disable_non_test_mouse(disable) {
   let utils = window.QueryInterface(Ci.nsIInterfaceRequestor)
                     .getInterface(Ci.nsIDOMWindowUtils);
   utils.disableNonTestMouseEvents(disable);
 }
 
 function* hover_icon(icon, tooltip) {
   disable_non_test_mouse(true);
@@ -92,17 +77,17 @@ add_task(function* unblock_icon_should_d
   info("- the suspend state of tab should be none-suspend -");
   yield ContentTask.spawn(tab.linkedBrowser, SuspendedType.NONE_SUSPENDED,
                           check_audio_suspended);
 
   info("- should not display unblocking icon -");
   yield waitForTabBlockEvent(tab, false);
 
   info("- should not display sound indicator icon -");
-  yield wait_for_tab_playing_event(tab, false);
+  yield waitForTabPlayingEvent(tab, false);
 
   info("- remove tab -");
   yield BrowserTestUtils.removeTab(tab);
 });
 
 add_task(function* should_not_show_sound_indicator_after_resume_tab() {
   info("- open new background tab -");
   let tab = window.gBrowser.addTab("about:blank");
@@ -122,13 +107,13 @@ add_task(function* should_not_show_sound
   info("- the suspend state of tab should be none-suspend -");
   yield ContentTask.spawn(tab.linkedBrowser, SuspendedType.NONE_SUSPENDED,
                           check_audio_suspended);
 
   info("- should not display unblocking icon -");
   yield waitForTabBlockEvent(tab, false);
 
   info("- should not display sound indicator icon -");
-  yield wait_for_tab_playing_event(tab, false);
+  yield waitForTabPlayingEvent(tab, false);
 
   info("- remove tab -");
   yield BrowserTestUtils.removeTab(tab);
 });