Add clearOriginJoinedAdInterestGroup to spec.bs (#844)

* Add clearOriginJoinedAdInterestGroup to spec.bs

This adds the explainer changes from explainer PR #829 / issue  #475 to the spec.

* Update spec.bs

Some cleanups - more likely to follow.

* Update spec.bs

* Update spec.bs

* Update spec.bs

Fix error?

* Update spec.bs

* Update spec.bs

* Update spec.bs

* Update spec.bs

* Update spec.bs

* Update spec.bs

* Update spec.bs

* Update spec.bs

* Update spec.bs

* Update spec.bs

spec.bs

@@ -346,7 +346,7 @@ This is detectable because it can change the set of fields that are read from th
   1. Let |permission| be the result of [=checking interest group permissions=] with
     |interestGroup|'s [=interest group/owner=], |frameOrigin|, and "`join`".
   1. If |permission| is false, then [=queue a task=] to [=reject=] |p| with a
-     "{{NotAllowedError}}" {{DOMException}} and do not run the remaining steps.
+     "{{NotAllowedError}}" {{DOMException}} and abort these steps.
   1. [=Queue a task=] to [=resolve=] |p| with `undefined`.
   1. If the browser is currently storing an interest group with `owner` and `name` that matches
     |interestGroup|, then set the [=interest group/bid counts=],
@@ -565,6 +565,8 @@ integer |maxIgs|:
 
 <h2 id="leaving-interest-groups">Leaving Interest Groups</h2>
 
+<h3 id="leaveadinterestgroup">leaveAdInterestGroup()</h3>
+
 *This first introductory paragraph is non-normative.*
 
 {{Window/navigator}}.{{Navigator/leaveAdInterestGroup()}} removes a user from a particular interest
@@ -608,15 +610,15 @@ The <dfn for=Navigator method>leaveAdInterestGroup(group)</dfn> method steps are
     "[=join-ad-interest-group=]" [=policy-controlled feature=], then [=exception/throw=] a
     "{{NotAllowedError}}" {{DOMException}}.
 
-    Note: both joining and leaving interest groups use the "join-ad-interest-group" feature.
+    Note: Both joining and leaving interest groups use the "join-ad-interest-group" feature.
   1. Let |owner| be the result of [=parsing an https origin=] with
     |group|["{{AuctionAdInterestGroupKey/owner}}"].
   1. If |owner| is failure, [=exception/throw=] a {{TypeError}}.
   1. Run these steps [=in parallel=]:
     1. Let |permission| be the result of [=checking interest group permissions=] with
       |owner|, |frameOrigin|, and "`leave`".
     1. If |permission| is false, then [=queue a task=] to [=reject=] |p| with a
-       "{{NotAllowedError}}" {{DOMException}} and do not run the remaining steps.
+       "{{NotAllowedError}}" {{DOMException}} and abort these steps.
     1. [=Queue a task=] to [=resolve=] |p| with `undefined`.
     1. [=list/Remove=] [=interest groups=] from the [=user agent=]'s [=interest group set=] whose
       [=interest group/owner=] is |owner| and [=interest group/name=] is
@@ -625,6 +627,54 @@ The <dfn for=Navigator method>leaveAdInterestGroup(group)</dfn> method steps are
 
 </div>
 
+<h3 id="clearoriginjoinedAdInterestGroups">clearOriginJoinedAdInterestGroups()</h3>
+
+*This first introductory paragraph is non-normative.*
+
+{{Window/navigator}}.{{Navigator/clearOriginJoinedAdInterestGroups()}} removes a user from
+[=interest groups=] whose [=interest group/joining origin=] is the associated
+{{Navigator}}'s [=relevant settings object=]'s [=environment/top-level origin=].
+
+
+<xmp class="idl">
+[SecureContext]
+partial interface Navigator {
+  Promise<undefined> clearOriginJoinedAdInterestGroups(
+      USVString owner, optional sequence<USVString> interestGroupsToKeep = []);
+};
+</xmp>
+
+<div algorithm>
+
+The <dfn for=Navigator method>clearOriginJoinedAdInterestGroups(|owner|, |interestGroupsToKeep|)</dfn>
+method steps are:
+
+1. Let |frameOrigin| be [=this=]'s [=relevant settings object=]'s
+  [=environment settings object/origin=].
+1. [=Assert=] that |frameOrigin| is not an [=opaque origin=] and its [=origin/scheme=] is "`https`".
+1. Let |p| be [=a new promise=].
+1. Let |global| be [=this=]'s [=relevant global object=].
+1. If |global|'s [=associated Document=] is not [=allowed to use=] the
+  "[=join-ad-interest-group=]" [=policy-controlled feature=], then [=exception/throw=] a
+  "{{NotAllowedError}}" {{DOMException}}.
+
+  Note: Both joining and leaving interest groups use the "join-ad-interest-group" feature.
+1. Let |ownerOrigin| be the result of [=parsing an https origin=] with |owner|.
+1. If |ownerOrigin| is failure, [=exception/throw=] a {{TypeError}}.
+1. Run these steps [=in parallel=]:
+  1. Let |permission| be the result of [=checking interest group permissions=] with
+    |ownerOrigin|, |frameOrigin|, and "`leave`".
+  1. If |permission| is false, then [=queue a global task=] on the [=DOM manipulation task source=]
+    given |global|, [=reject=] |p| with a "{{NotAllowedError}}" {{DOMException}} and abort these steps.
+  1. [=Queue a global task=] on the [=DOM manipulation task source=] given |global|, to [=resolve=] |p|
+    with {{undefined}}.
+  1. [=list/Remove=] [=interest groups=] from the [=user agent=]'s [=interest group set=]
+    whose [=interest group/owner=] is |ownerOrigin|, whose [=interest group/joining origin=] is
+    |frameOrigin|, and whose [=interest group/name=] is not in |interestGroupsToKeep|.
+1. Return |p|.
+
+</div>
+
 <h2 id="running-ad-auctions">Running Ad Auctions</h2>
 
 *This first introductory paragraph is non-normative.*