Spec: export obtain the Private Aggregation coordinator algorithm (#163)

The version that takes a USVString is shared between Protected Audience
and Shared Storage, so we can export it. Also updates the name of the 
monkey patched version, which will be removed from this spec soon.

Author: alexmturner

spec.bs

@@ -641,6 +641,24 @@ an [=origin=] |origin|, perform the following steps. They return a [=boolean=].
 
 </div>
 
+<div algorithm>
+To <dfn export>obtain the Private Aggregation coordinator</dfn> given a
+{{USVString}} |originString|, perform the following steps. They return an
+[=aggregation coordinator=] or a {{DOMException}}.
+
+1. Let |url| be the result of running the [=URL parser=] on |originString|.
+1. If |url| is failure or null, return a new {{DOMException}} with name
+    "`SyntaxError`".
+
+    Issue: Consider throwing an error if the path is not empty.
+1. Let |origin| be |url|'s [=url/origin=].
+1. If the result of [=determining if an origin is an aggregation coordinator=]
+    given |origin| is false, return a new {{DOMException}} with name
+    "`DataError`".
+1. Return |origin|.
+
+</div>
+
 <div algorithm>
 To <dfn export>set the aggregation coordinator for a batching scope</dfn> given
 an [=origin=] |origin| and a [=batching scope=] |batchingScope|:
@@ -1513,8 +1531,8 @@ following steps at the end of the scope nested under step 5 ("Validate the given
 <div algorithm="protected-audience-joinadig-monkey-patch">
 17. If |group|["{{AuctionAdInterestGroup/privateAggregationConfig}}"]
     [=map/exists=]:
-    1. Let |aggregationCoordinator| be the result of [=obtaining the Private
-        Aggregation coordinator=] given
+    1. Let |aggregationCoordinator| be the result of [=obtaining the coordinator
+        from a Private Aggregation config=] given
         |group|["{{AuctionAdInterestGroup/privateAggregationConfig}}"].
     1. If |aggregationCoordinator| is a {{DOMException}}, then
         [=exception/throw=] |aggregationCoordinator|.
@@ -1610,8 +1628,8 @@ modified to add the following steps just before the last step ("Return
         : [=debug details/key=]
         :: |debugKey|
 1. If |config|["{{AuctionAdConfig/privateAggregationConfig}}"] [=map/exists=]:
-    1. Let |aggregationCoordinator| be the result of [=obtaining the Private
-        Aggregation coordinator=] given
+    1. Let |aggregationCoordinator| be the result of [=obtaining the coordinator
+        from a Private Aggregation config=] given
         |config|["{{AuctionAdConfig/privateAggregationConfig}}"].
     1. If |aggregationCoordinator| is a {{DOMException}}, return failure.
     1. Set <var ignore>auctionConfig</var>'s [=auction config/seller Private
@@ -1781,8 +1799,7 @@ steps are modified to add the following case at the end of the "Switch on
     1. If |value|["`aggregationCoordinatorOrigin`"] [=map/exists=]:
         1. If |value|["`aggregationCoordinatorOrigin`"] is not a [=string=],
             jump to the step labeled Abort update.
-        1. Let |aggregationCoordinator| be the result of [=obtain the Private
-            Aggregation coordinator from a string|obtaining the Private
+        1. Let |aggregationCoordinator| be the result of [=obtaining the Private
             Aggregation coordinator=] given
             |value|["`aggregationCoordinatorOrigin`"].
         1. If |aggregationCoordinator| is a {{DOMException}}, jump to the step
@@ -2119,37 +2136,17 @@ They return an [=interest group=] or null:
 </div>
 
 <div algorithm>
-To <dfn>obtain the Private Aggregation coordinator</dfn> given a
+To <dfn>obtain the coordinator from a Private Aggregation config</dfn> given a
 {{ProtectedAudiencePrivateAggregationConfig}} |config|, perform the following
 steps. They return an [=aggregation coordinator=], null or a {{DOMException}}.
 
 1. If |config|["{{ProtectedAudiencePrivateAggregationConfig/aggregationCoordinatorOrigin}}"]
     does not [=map/exist=], return null.
-1. Return the result of [=obtain the Private Aggregation coordinator from a
-    string|obtaining the Private Aggregation coordinator=] given
+1. Return the result of [=obtaining the Private Aggregation coordinator=] given
     |config|["{{ProtectedAudiencePrivateAggregationConfig/aggregationCoordinatorOrigin}}"].
 
 </div>
 
-<div algorithm>
-To <dfn lt="obtain the Private Aggregation coordinator from a string">obtain the
-Private Aggregation coordinator</dfn> given a {{USVString}} |originString|,
-perform the following steps. They return an [=aggregation coordinator=] or a
-{{DOMException}}.
-
-1. Let |url| be the result of running the [=URL parser=] on |originString|.
-1. If |url| is failure or null, return a new {{DOMException}} with name
-    "`SyntaxError`".
-
-    Issue: Consider throwing an error if the path is not empty.
-1. Let |origin| be |url|'s [=url/origin=].
-1. If the result of [=determining if an origin is an aggregation coordinator=]
-    given |origin| is false, return a new {{DOMException}} with name
-    "`DataError`".
-1. Return |origin|.
-
-</div>
-
 Privacy considerations {#privacy-considerations}
 ================================================