diff --git a/toolkit/components/extensions/test/xpcshell/head_telemetry.js b/toolkit/components/extensions/test/xpcshell/head_telemetry.js
deleted file mode 100644
index 98b87d14d54d..000000000000
--- a/toolkit/components/extensions/test/xpcshell/head_telemetry.js
+++ /dev/null
@@ -1,34 +0,0 @@
-/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* vim: set sts=2 sw=2 et tw=80: */
-"use strict";
-
-/* exported IS_OOP, arraySum, clearHistograms, getSnapshots, promiseTelemetryRecorded */
-
-XPCOMUtils.defineLazyModuleGetter(this, "ContentTaskUtils",
-                                  "resource://testing-common/ContentTaskUtils.jsm");
-
-const IS_OOP = Services.prefs.getBoolPref("extensions.webextensions.remote");
-
-function arraySum(arr) {
-  return arr.reduce((a, b) => a + b, 0);
-}
-
-function clearHistograms() {
-  Services.telemetry.snapshotSubsessionHistograms(true);
-}
-
-function getSnapshots(process) {
-  return Services.telemetry.snapshotSubsessionHistograms()[process];
-}
-
-// There is no good way to make sure that the parent received the histogram
-// entries from the extension and content processes.
-// Let's stick to the ugly, spinning the event loop until we have a good
-// approach (Bug 1357509).
-function promiseTelemetryRecorded(id, process, expectedCount) {
-  let condition = () => {
-    let snapshot = Services.telemetry.snapshotSubsessionHistograms()[process][id];
-    return snapshot && arraySum(snapshot.counts) >= expectedCount;
-  };
-  return ContentTaskUtils.waitForCondition(condition);
-}
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_extension_content_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_extension_content_telemetry.js
index fc71a40a6f10..91dae96deabf 100644
--- a/toolkit/components/extensions/test/xpcshell/test_ext_extension_content_telemetry.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extension_content_telemetry.js
@@ -41,35 +41,32 @@ add_task(async function test_telemetry() {
     },
   });
 
-  clearHistograms();
-
-  let process = IS_OOP ? "content" : "parent";
-  ok(!(HISTOGRAM in getSnapshots(process)), `No data recorded for histogram: ${HISTOGRAM}.`);
+  let histogram = Services.telemetry.getHistogramById(HISTOGRAM);
+  histogram.clear();
+  equal(histogram.snapshot().sum, 0,
+        `No data recorded for histogram: ${HISTOGRAM}.`);
 
   await extension1.startup();
-  ok(!(HISTOGRAM in getSnapshots(process)),
-     `No data recorded for histogram after startup: ${HISTOGRAM}.`);
+  equal(histogram.snapshot().sum, 0,
+        `No data recorded for histogram after startup: ${HISTOGRAM}.`);
 
   let contentPage = await ExtensionTestUtils.loadContentPage(`${BASE_URL}/file_sample.html`);
   await extension1.awaitMessage("content-script-run");
-  await promiseTelemetryRecorded(HISTOGRAM, process, 1);
-
-  equal(arraySum(getSnapshots(process)[HISTOGRAM].counts), 1,
-        `Data recorded for histogram: ${HISTOGRAM}.`);
+  let histogramSum = histogram.snapshot().sum;
+  ok(histogramSum > 0,
+     `Data recorded for first extension for histogram: ${HISTOGRAM}.`);
 
   await contentPage.close();
   await extension1.unload();
 
   await extension2.startup();
-  equal(arraySum(getSnapshots(process)[HISTOGRAM].counts), 1,
+  equal(histogram.snapshot().sum, histogramSum,
         `No data recorded for histogram after startup: ${HISTOGRAM}.`);
 
   contentPage = await ExtensionTestUtils.loadContentPage(`${BASE_URL}/file_sample.html`);
   await extension2.awaitMessage("content-script-run");
-  await promiseTelemetryRecorded(HISTOGRAM, process, 2);
-
-  equal(arraySum(getSnapshots(process)[HISTOGRAM].counts), 2,
-        `Data recorded for histogram: ${HISTOGRAM}.`);
+  ok(histogram.snapshot().sum > histogramSum,
+     `Data recorded for second extension for histogram: ${HISTOGRAM}.`);
 
   await contentPage.close();
   await extension2.unload();
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js
index cce0499c4378..3d335cf756dc 100644
--- a/toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js
@@ -6,6 +6,10 @@ const HISTOGRAM_IDS = [
   "WEBEXT_STORAGE_LOCAL_SET_MS", "WEBEXT_STORAGE_LOCAL_GET_MS",
 ];
 
+function arraySum(arr) {
+  return arr.reduce((a, b) => a + b, 0);
+}
+
 add_task(async function test_telemetry_background() {
   const server = createHttpServer();
   server.registerDirectory("/data/", do_get_file("data"));
@@ -45,58 +49,44 @@ add_task(async function test_telemetry_background() {
   let extension1 = ExtensionTestUtils.loadExtension(extInfo);
   let extension2 = ExtensionTestUtils.loadExtension(extInfo);
 
-  clearHistograms();
-
-  let process = IS_OOP ? "extension" : "parent";
-  let snapshots = getSnapshots(process);
+  // Initialize and clear histograms.
+  let histograms = {};
   for (let id of HISTOGRAM_IDS) {
-    ok(!(id in snapshots), `No data recorded for histogram: ${id}.`);
+    histograms[id] = Services.telemetry.getHistogramById(id);
+    histograms[id].clear();
+    equal(arraySum(histograms[id].snapshot().counts), 0,
+          `No data recorded for histogram: ${id}.`);
   }
 
   await extension1.startup();
   await extension1.awaitMessage("backgroundDone");
-  for (let id of HISTOGRAM_IDS) {
-    await promiseTelemetryRecorded(id, process, 1);
-  }
 
   // Telemetry from extension1's background page should be recorded.
-  snapshots = getSnapshots(process);
-  for (let id of HISTOGRAM_IDS) {
-    equal(arraySum(snapshots[id].counts), 1,
+  for (let id in histograms) {
+    equal(arraySum(histograms[id].snapshot().counts), 1,
           `Data recorded for histogram: ${id}.`);
   }
 
   await extension2.startup();
   await extension2.awaitMessage("backgroundDone");
-  for (let id of HISTOGRAM_IDS) {
-    await promiseTelemetryRecorded(id, process, 2);
-  }
 
   // Telemetry from extension2's background page should be recorded.
-  snapshots = getSnapshots(process);
-  for (let id of HISTOGRAM_IDS) {
-    equal(arraySum(snapshots[id].counts), 2,
+  for (let id in histograms) {
+    equal(arraySum(histograms[id].snapshot().counts), 2,
           `Additional data recorded for histogram: ${id}.`);
   }
 
   await extension2.unload();
 
   // Run a content script.
-  process = IS_OOP ? "content" : "parent";
-  let expectedCount = IS_OOP ? 1 : 3;
   let contentScriptPromise = extension1.awaitMessage("contentDone");
   let contentPage = await ExtensionTestUtils.loadContentPage(`${BASE_URL}/file_sample.html`);
   await contentScriptPromise;
   await contentPage.close();
 
-  for (let id of HISTOGRAM_IDS) {
-    await promiseTelemetryRecorded(id, process, expectedCount);
-  }
-
   // Telemetry from extension1's content script should be recorded.
-  snapshots = getSnapshots(process);
-  for (let id of HISTOGRAM_IDS) {
-    equal(arraySum(snapshots[id].counts), expectedCount,
+  for (let id in histograms) {
+    equal(arraySum(histograms[id].snapshot().counts), 3,
           `Data recorded in content script for histogram: ${id}.`);
   }
 
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
index cdcec1149805..c8f290f67347 100644
--- a/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
@@ -13,7 +13,6 @@ skip-if = os == "android" # Android does not use Places for history.
 [test_ext_background_telemetry.js]
 [test_ext_background_window_properties.js]
 skip-if = os == "android"
-[test_ext_browserSettings.js]
 [test_ext_contextual_identities.js]
 skip-if = os == "android" # Containers are not exposed to android.
 [test_ext_debugging_utils.js]
@@ -28,7 +27,6 @@ skip-if = os == "android"
 [test_ext_extension.js]
 [test_ext_extensionPreferencesManager.js]
 [test_ext_extensionSettingsStore.js]
-[test_ext_extension_content_telemetry.js]
 [test_ext_extension_startup_telemetry.js]
 [test_ext_idle.js]
 [test_ext_legacy_extension_context.js]
@@ -58,7 +56,6 @@ head = head.js head_sync.js
 skip-if = os == "android"
 [test_ext_storage_sync_crypto.js]
 skip-if = os == "android"
-[test_ext_storage_telemetry.js]
 [test_ext_topSites.js]
 skip-if = os == "android"
 [test_native_messaging.js]
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini
index 31cec2a7e1c0..8af28a476edc 100644
--- a/toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini
@@ -1,5 +1,5 @@
 [DEFAULT]
-head = head.js head_remote.js head_e10s.js head_telemetry.js
+head = head.js head_remote.js head_e10s.js
 tail =
 firefox-appdir = browser
 skip-if = appname == "thunderbird" || os == "android"
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell.ini b/toolkit/components/extensions/test/xpcshell/xpcshell.ini
index c5d4680c0786..b9ee0c04a497 100644
--- a/toolkit/components/extensions/test/xpcshell/xpcshell.ini
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell.ini
@@ -1,5 +1,5 @@
 [DEFAULT]
-head = head.js head_telemetry.js
+head = head.js
 firefox-appdir = browser
 skip-if = appname == "thunderbird"
 dupe-manifest =