Clear electron data when logging out (#10386)

src/BasePlatform.ts

@@ -442,4 +442,12 @@ export default abstract class BasePlatform {
             logger.error("idbDelete failed in destroyPickleKey", e);
         }
     }
+
+    /**
+     * Clear app storage, called when logging out to perform data clean up.
+     */
+    public async clearStorage(): Promise<void> {
+        window.sessionStorage.clear();
+        window.localStorage.clear();
+    }
 }

src/Lifecycle.ts

@@ -862,6 +862,7 @@ export async function onLoggedOut(): Promise<void> {
     stopMatrixClient();
     await clearStorage({ deleteEverything: true });
     LifecycleCustomisations.onLoggedOutAndStorageCleared?.();
+    await PlatformPeg.get()?.clearStorage();
 
     // Do this last, so we can make sure all storage has been cleared and all
     // customisations got the memo.