Bug 1252998 - Use hosts instead of principals to delete ServiceWorkers in the SiteDataManager. r=baku

site.principals is not always guaranteed to contain elements, only if
the site has quota storage or AppCache. This patch simplifies the function
to use hosts instead.

browser/modules/SiteDataManager.jsm

@@ -29,7 +29,8 @@ var SiteDataManager = {
   // A Map of sites and their disk usage according to Quota Manager and appcache
   // Key is host (group sites based on host across scheme, port, origin atttributes).
   // Value is one object holding:
-  //   - principals: instances of nsIPrincipal.
+  //   - principals: instances of nsIPrincipal (only when the site has
+  //     quota storage or AppCache).
   //   - persisted: the persistent-storage status.
   //   - quotaUsage: the usage of indexedDB and localStorage.
   //   - appCacheList: an array of app cache; instances of nsIApplicationCache
@@ -314,14 +315,6 @@ var SiteDataManager = {
     site.cookies = [];
   },
 
-  _removeServiceWorkersForSites(sites) {
-    let promises = [];
-    sites.forEach(s => {
-      promises.push(ServiceWorkerCleanUp.removeFromHost(s.principals[0].URI.host));
-    });
-    return Promise.all(promises);
-  },
-
   /**
    * Removes all site data for the specified list of hosts.
    *
@@ -335,29 +328,24 @@ var SiteDataManager = {
     this._updateAppCache();
 
     let unknownHost = "";
-    let targetSites = new Map();
+    let promises = [];
     for (let host of hosts) {
       let site = this._sites.get(host);
       if (site) {
+        // Clear localstorage.
+        Services.obs.notifyObservers(null, "browser:purge-domain-data", host);
         this._removePermission(site);
         this._removeAppCache(site);
         this._removeCookies(site);
-        Services.obs.notifyObservers(null, "browser:purge-domain-data", host);
-        targetSites.set(host, site);
+        promises.push(ServiceWorkerCleanUp.removeFromHost(host));
+        promises.push(this._removeQuotaUsage(site));
       } else {
         unknownHost = host;
         break;
       }
     }
 
-    if (targetSites.size > 0) {
-      await this._removeServiceWorkersForSites(targetSites);
-      let promises = [];
-      for (let [, site] of targetSites) {
-        promises.push(this._removeQuotaUsage(site));
-      }
-      await Promise.all(promises);
-    }
+    await Promise.all(promises);
 
     if (unknownHost) {
       throw `SiteDataManager: removing unknown site of ${unknownHost}`;
@@ -421,6 +409,7 @@ var SiteDataManager = {
    * Clears all site data, which currently means
    *   - Cookies
    *   - AppCache
+   *   - LocalStorage
    *   - ServiceWorkers
    *   - Quota Managed Storage
    *   - persistent-storage permissions
@@ -428,6 +417,9 @@ var SiteDataManager = {
    * @returns a Promise that resolves with the cache size on disk in bytes
    */
   async removeSiteData() {
+    // LocalStorage
+    Services.obs.notifyObservers(null, "extension:purge-localStorage");
+
     Services.cookies.removeAll();
     OfflineAppCacheHelper.clear();