--- a/devtools/server/tests/browser/browser.ini
+++ b/devtools/server/tests/browser/browser.ini
@@ -59,21 +59,18 @@ skip-if = e10s # Bug 1183605 - devtools/
 [browser_canvasframe_helper_05.js]
 skip-if = e10s # Bug 1183605 - devtools/server/tests/browser/ tests are still disabled in E10S
 [browser_canvasframe_helper_06.js]
 skip-if = e10s # Bug 1183605 - devtools/server/tests/browser/ tests are still disabled in E10S
 [browser_layout_getGrids.js]
 [browser_layout_simple.js]
 [browser_markers-cycle-collection.js]
 [browser_markers-docloading-01.js]
-uses-unsafe-cpows = true
 [browser_markers-docloading-02.js]
-uses-unsafe-cpows = true
 [browser_markers-docloading-03.js]
-uses-unsafe-cpows = true
 [browser_markers-gc.js]
 [browser_markers-minor-gc.js]
 [browser_markers-parse-html.js]
 [browser_markers-styles.js]
 [browser_markers-timestamp.js]
 [browser_navigateEvents.js]
 skip-if = e10s # Bug 1183605 - devtools/server/tests/browser/ tests are still disabled in E10S
 [browser_perf-01.js]

--- a/devtools/server/tests/browser/browser_markers-docloading-01.js
+++ b/devtools/server/tests/browser/browser_markers-docloading-01.js
@@ -6,29 +6,30 @@
  */
 "use strict";
 
 const { TimelineFront } = require("devtools/shared/fronts/timeline");
 const MARKER_NAMES = ["document::DOMContentLoaded", "document::Load"];
 
 add_task(async function() {
   let browser = await addTab(MAIN_DOMAIN + "doc_innerHTML.html");
-  let doc = browser.contentDocumentAsCPOW;
 
   initDebuggerServer();
   let client = new DebuggerClient(DebuggerServer.connectPipe());
   let form = await connectDebuggerClient(client);
   let front = TimelineFront(client, form);
   let rec = await front.start({ withMarkers: true });
 
   front.once("doc-loading", e => {
     ok(false, "Should not be emitting doc-loading events.");
   });
 
-  executeSoon(() => doc.location.reload());
+  ContentTask.spawn(browser, null, function() {
+    content.location.reload();
+  });
 
   await waitForMarkerType(front, MARKER_NAMES, () => true, e => e, "markers");
   await front.stop(rec);
 
   ok(true, "Found the required marker names.");
 
   // Wait some more time to make sure the 'doc-loading' events never get fired.
   await DevToolsUtils.waitForTime(1000);

--- a/devtools/server/tests/browser/browser_markers-docloading-02.js
+++ b/devtools/server/tests/browser/browser_markers-docloading-02.js
@@ -6,27 +6,28 @@
  */
 "use strict";
 
 const { TimelineFront } = require("devtools/shared/fronts/timeline");
 const MARKER_NAMES = ["document::DOMContentLoaded", "document::Load"];
 
 add_task(async function() {
   let browser = await addTab(MAIN_DOMAIN + "doc_innerHTML.html");
-  let doc = browser.contentDocumentAsCPOW;
 
   initDebuggerServer();
   let client = new DebuggerClient(DebuggerServer.connectPipe());
   let form = await connectDebuggerClient(client);
   let front = TimelineFront(client, form);
   let rec = await front.start({ withMarkers: true, withDocLoadingEvents: true });
 
   await new Promise(resolve => {
     front.once("doc-loading", resolve);
-    doc.location.reload();
+    ContentTask.spawn(browser, null, function() {
+      content.location.reload();
+    });
   });
 
   ok(true, "At least one doc-loading event got fired.");
 
   await waitForMarkerType(front, MARKER_NAMES, () => true, e => e, "markers");
   await front.stop(rec);
 
   ok(true, "Found the required marker names.");

--- a/devtools/server/tests/browser/browser_markers-docloading-03.js
+++ b/devtools/server/tests/browser/browser_markers-docloading-03.js
@@ -6,31 +6,32 @@
  */
 "use strict";
 
 const { TimelineFront } = require("devtools/shared/fronts/timeline");
 const MARKER_NAMES = ["document::DOMContentLoaded", "document::Load"];
 
 add_task(async function() {
   let browser = await addTab(MAIN_DOMAIN + "doc_innerHTML.html");
-  let doc = browser.contentDocumentAsCPOW;
 
   initDebuggerServer();
   let client = new DebuggerClient(DebuggerServer.connectPipe());
   let form = await connectDebuggerClient(client);
   let front = TimelineFront(client, form);
   let rec = await front.start({ withDocLoadingEvents: true });
 
   waitForMarkerType(front, MARKER_NAMES, () => true, e => e, "markers").then(e => {
     ok(false, "Should not be emitting doc-loading markers.");
   });
 
   await new Promise(resolve => {
     front.once("doc-loading", resolve);
-    doc.location.reload();
+    ContentTask.spawn(browser, null, function() {
+      content.location.reload();
+    });
   });
 
   ok(true, "At least one doc-loading event got fired.");
 
   await front.stop(rec);
 
   // Wait some more time to make sure the 'doc-loading' markers never get fired.
   await DevToolsUtils.waitForTime(1000);