support other SQLite wrappers, and various hooks needed by grist-static (#516)

app/client/components/GristWSConnection.ts

@@ -1,11 +1,12 @@
 import {get as getBrowserGlobals} from 'app/client/lib/browserGlobals';
 import {guessTimezone} from 'app/client/lib/guessTimezone';
 import {getSessionStorage} from 'app/client/lib/storage';
+import {newUserAPIImpl} from 'app/client/models/AppModel';
 import {getWorker} from 'app/client/models/gristConfigCache';
 import {CommResponseBase} from 'app/common/CommTypes';
 import * as gutil from 'app/common/gutil';
 import {addOrgToPath, docUrl, getGristConfig} from 'app/common/urlUtils';
-import {UserAPI, UserAPIImpl} from 'app/common/UserAPI';
+import {UserAPI} from 'app/common/UserAPI';
 import {Events as BackboneEvents} from 'backbone';
 import {Disposable} from 'grainjs';
 
@@ -25,7 +26,7 @@ async function getDocWorkerUrl(assignmentId: string|null): Promise<string|null>
   // never changes.
   if (assignmentId === null) { return docUrl(null); }
 
-  const api: UserAPI = new UserAPIImpl(getGristConfig().homeUrl!);
+  const api: UserAPI = newUserAPIImpl();
   return getWorker(api, assignmentId);
 }
 

app/client/components/WidgetFrame.ts

@@ -1,5 +1,6 @@
 import BaseView from 'app/client/components/BaseView';
 import {GristDoc} from 'app/client/components/GristDoc';
+import {hooks} from 'app/client/Hooks';
 import {get as getBrowserGlobals} from 'app/client/lib/browserGlobals';
 import {ColumnRec, ViewSectionRec} from 'app/client/models/DocModel';
 import {AccessLevel, isSatisfied} from 'app/common/CustomWidget';
@@ -157,6 +158,7 @@ export class WidgetFrame extends DisposableWithEvents {
     return onElem(
       (this._iframe = dom('iframe', dom.cls('clipboard_focus'), dom.cls('custom_view'), {
         src: fullUrl,
+        ...hooks.iframeAttributes,
       }))
     );
   }