diff --git a/extensions/permissions/nsPermissionManager.cpp b/extensions/permissions/nsPermissionManager.cpp
index bfec5f71e623..b43f1172edb7 100644
--- a/extensions/permissions/nsPermissionManager.cpp
+++ b/extensions/permissions/nsPermissionManager.cpp
@@ -2997,55 +2997,6 @@ void nsPermissionManager::UpdateDB(
   MOZ_ASSERT(NS_SUCCEEDED(rv));
 }
 
-NS_IMETHODIMP
-nsPermissionManager::UpdateExpireTime(nsIPrincipal* aPrincipal,
-                                      const nsACString& aType,
-                                      bool aExactHostMatch,
-                                      uint64_t aSessionExpireTime,
-                                      uint64_t aPersistentExpireTime) {
-  NS_ENSURE_ARG_POINTER(aPrincipal);
-
-  uint64_t nowms = PR_Now() / 1000;
-  if (aSessionExpireTime < nowms || aPersistentExpireTime < nowms) {
-    return NS_ERROR_INVALID_ARG;
-  }
-
-  if (nsContentUtils::IsSystemPrincipal(aPrincipal)) {
-    return NS_OK;
-  }
-
-  // Setting the expire time of an nsEP is non-sensical.
-  if (IsExpandedPrincipal(aPrincipal)) {
-    return NS_ERROR_INVALID_ARG;
-  }
-
-  MOZ_ASSERT(PermissionAvailable(aPrincipal, aType));
-
-  int32_t typeIndex = GetTypeIndex(aType, false);
-  // If type == -1, the type isn't known,
-  // so just return NS_OK
-  if (typeIndex == -1) return NS_OK;
-
-  PermissionHashKey* entry =
-      GetPermissionHashKey(aPrincipal, typeIndex, aExactHostMatch);
-  if (!entry) {
-    return NS_OK;
-  }
-
-  int32_t idx = entry->GetPermissionIndex(typeIndex);
-  if (-1 == idx) {
-    return NS_OK;
-  }
-
-  PermissionEntry& perm = entry->GetPermissions()[idx];
-  if (perm.mExpireType == EXPIRE_TIME) {
-    perm.mExpireTime = aPersistentExpireTime;
-  } else if (perm.mExpireType == EXPIRE_SESSION && perm.mExpireTime != 0) {
-    perm.mExpireTime = aSessionExpireTime;
-  }
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 nsPermissionManager::GetPermissionsWithKey(const nsACString& aPermissionKey,
                                            nsTArray<IPC::Permission>& aPerms) {
diff --git a/extensions/permissions/test/unit/test_permmanager_expiration.js b/extensions/permissions/test/unit/test_permmanager_expiration.js
index c7acdb986ba4..6b03382333d8 100644
--- a/extensions/permissions/test/unit/test_permmanager_expiration.js
+++ b/extensions/permissions/test/unit/test_permmanager_expiration.js
@@ -84,38 +84,6 @@ function* do_run_test() {
     0
   );
 
-  // add a permission for renewal
-  pm.addFromPrincipal(
-    principal,
-    "test/expiration-perm-renewable",
-    1,
-    pm.EXPIRE_TIME,
-    now + 100
-  );
-  pm.addFromPrincipal(
-    principal,
-    "test/expiration-session-renewable",
-    1,
-    pm.EXPIRE_SESSION,
-    now + 100
-  );
-
-  // And immediately renew them with longer timeouts
-  pm.updateExpireTime(
-    principal,
-    "test/expiration-perm-renewable",
-    true,
-    now + 100,
-    now + 1e6
-  );
-  pm.updateExpireTime(
-    principal,
-    "test/expiration-session-renewable",
-    true,
-    now + 1e6,
-    now + 100
-  );
-
   // check that the second two haven't expired yet
   Assert.equal(
     1,
@@ -129,17 +97,6 @@ function* do_run_test() {
     1,
     pm.testPermissionFromPrincipal(principal, "test/expiration-perm-nexp")
   );
-  Assert.equal(
-    1,
-    pm.testPermissionFromPrincipal(principal, "test/expiration-perm-renewable")
-  );
-  Assert.equal(
-    1,
-    pm.testPermissionFromPrincipal(
-      principal,
-      "test/expiration-session-renewable"
-    )
-  );
 
   // ... and the first one has
   do_timeout(10, continue_test);
@@ -183,18 +140,5 @@ function* do_run_test() {
     pm.getPermissionObject(principal, "test/expiration-session-exp2", false)
   );
 
-  // Check that the renewable permissions actually got renewed
-  Assert.equal(
-    1,
-    pm.testPermissionFromPrincipal(principal, "test/expiration-perm-renewable")
-  );
-  Assert.equal(
-    1,
-    pm.testPermissionFromPrincipal(
-      principal,
-      "test/expiration-session-renewable"
-    )
-  );
-
   do_finish_generator_test(test_generator);
 }
diff --git a/netwerk/base/nsIPermissionManager.idl b/netwerk/base/nsIPermissionManager.idl
index cbba65afa7fd..b13ce5606560 100644
--- a/netwerk/base/nsIPermissionManager.idl
+++ b/netwerk/base/nsIPermissionManager.idl
@@ -198,26 +198,6 @@ interface nsIPermissionManager : nsISupports
    */
   readonly attribute Array<nsIPermission> all;
 
-  /**
-   * If the current permission is set to expire, reset the expiration time. If
-   * there is no permission or the current permission does not expire, this
-   * method will silently return.
-   *
-   * @param sessionExpiretime  an integer representation of when this permission
-   *                           should be forgotten (milliseconds since
-   *                           Jan 1 1970 0:00:00), if it is currently
-   *                           EXPIRE_SESSION.
-   * @param sessionExpiretime  an integer representation of when this permission
-   *                           should be forgotten (milliseconds since
-   *                           Jan 1 1970 0:00:00), if it is currently
-   *                           EXPIRE_TIME.
-   */
-  void updateExpireTime(in nsIPrincipal principal,
-                        in ACString type,
-                        in boolean exactHost,
-                        in uint64_t sessionExpireTime,
-                        in uint64_t persistentExpireTime);
-
   /**
    * The content process doesn't have access to every permission. Instead, when
    * LOAD_DOCUMENT_URI channels for http://, https://, and ftp:// URIs are