diff --git a/screen-capture/getdisplaymedia.https.html b/screen-capture/getdisplaymedia.https.html
index 06ab72d20bf266..36e0f22933a089 100644
--- a/screen-capture/getdisplaymedia.https.html
+++ b/screen-capture/getdisplaymedia.https.html
@@ -7,8 +7,8 @@
   'use strict';
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
-  const stream = await navigator.getDisplayMedia({video: true});
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
+  const stream = await navigator.mediaDevices.getDisplayMedia({video: true});
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
   assert_equals(stream.getTracks().length, 1);
@@ -22,8 +22,8 @@
 // Note that this results in some non-intuitive cases returning a video track,
 // i.e. {video: false}.
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
-  const stream = await navigator.getDisplayMedia();
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
+  const stream = await navigator.mediaDevices.getDisplayMedia();
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
   assert_equals(stream.getTracks().length, 1);
@@ -32,8 +32,8 @@
 }, 'getDisplayMedia() with no constraints');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
-  const stream = await navigator.getDisplayMedia({video: false});
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
+  const stream = await navigator.mediaDevices.getDisplayMedia({video: false});
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
   assert_equals(stream.getTracks().length, 1);
@@ -42,8 +42,8 @@
 }, 'getDisplayMedia() with video false');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
-  const stream = await navigator.getDisplayMedia({audio: false});
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
+  const stream = await navigator.mediaDevices.getDisplayMedia({audio: false});
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
   assert_equals(stream.getTracks().length, 1);
@@ -52,8 +52,8 @@
 }, 'getDisplayMedia() with audio false');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
-  const stream = await navigator.getDisplayMedia({audio: true});
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
+  const stream = await navigator.mediaDevices.getDisplayMedia({audio: true});
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
   assert_equals(stream.getTracks().length, 1);
@@ -62,10 +62,10 @@
 }, 'getDisplayMedia() with audio true');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
   try {
-    const stream =
-        await navigator.getDisplayMedia({video: {advanced: [{zoom: 1}]}});
+    const stream = await navigator.mediaDevices.getDisplayMedia(
+        {video: {advanced: [{zoom: 1}]}});
   } catch (err) {
     assert_equals(err.name, 'TypeError');
     return;
@@ -74,10 +74,10 @@
 }, 'getDisplayMedia() with advanced constraint');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
   try {
-    const stream =
-        await navigator.getDisplayMedia({video: {width: {min: 360}}});
+    const stream = await navigator.mediaDevices.getDisplayMedia(
+        {video: {width: {min: 360}}});
   } catch (err) {
     assert_equals(err.name, 'TypeError');
     return;
@@ -86,10 +86,10 @@
 }, 'getDisplayMedia() with min constraint');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
   try {
-    const stream =
-        await navigator.getDisplayMedia({video: {width: {exact: 360}}});
+    const stream = await navigator.mediaDevices.getDisplayMedia(
+        {video: {width: {exact: 360}}});
   } catch (err) {
     assert_equals(err.name, 'TypeError');
     return;
@@ -98,10 +98,10 @@
 }, 'getDisplayMedia() with exact constraint');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
   const maxWidth = 360;
-  const stream =
-      await navigator.getDisplayMedia({video: {width: {max: maxWidth}}});
+  const stream = await navigator.mediaDevices.getDisplayMedia(
+      {video: {width: {max: maxWidth}}});
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
   assert_equals(stream.getVideoTracks().length, 1);
@@ -111,10 +111,10 @@
 }, 'getDisplayMedia() with max constraint');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
   const maxWidth = 360;
   const maxFrameRate = 4;
-  const stream = await navigator.getDisplayMedia(
+  const stream = await navigator.mediaDevices.getDisplayMedia(
       {video: {width: {max: maxWidth}, frameRate: {max: maxFrameRate}}});
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
@@ -126,9 +126,10 @@
 }, 'getDisplayMedia() with constraints applied');
 
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
   try {
-    const stream = await navigator.getDisplayMedia({video: {width: {max: 0}}});
+    const stream = await navigator.mediaDevices.getDisplayMedia(
+        {video: {width: {max: 0}}});
   } catch (err) {
     assert_equals(err.name, 'OverconstrainedError');
     return;
@@ -138,8 +139,8 @@
 
 // Content shell picks a fake desktop device by default.
 promise_test(async t => {
-  assert_idl_attribute(navigator, 'getDisplayMedia');
-  const stream = await navigator.getDisplayMedia({video: true});
+  assert_idl_attribute(navigator.mediaDevices, 'getDisplayMedia');
+  const stream = await navigator.mediaDevices.getDisplayMedia({video: true});
   const [track] = stream.getTracks();
   t.add_cleanup(() => track.stop());
   assert_equals(stream.getVideoTracks().length, 1);
diff --git a/screen-capture/idlharness.window.js b/screen-capture/idlharness.window.js
index 076e89f275c9e5..a9448353ec355b 100644
--- a/screen-capture/idlharness.window.js
+++ b/screen-capture/idlharness.window.js
@@ -10,7 +10,7 @@ idl_test(
   ['mediacapture-streams', 'html'],
   idl_array => {
     idl_array.add_objects({
-      Navigator: ['navigator'],
+      MediaDevices: ['navigator.mediaDevices'],
     });
   }
 );