Bug 736456 - Cache the spec in captureAndStore, since currentURI may not be available later; r=ttaubert

browser/components/thumbnails/PageThumbs.jsm

@@ -109,6 +109,7 @@ let PageThumbs = {
    * @param aCallback The function to be called when finished (optional).
    */
   captureAndStore: function PageThumbs_captureAndStore(aBrowser, aCallback) {
+    let url = aBrowser.currentURI.spec;
     this.capture(aBrowser.contentWindow, function (aInputStream) {
       let telemetryStoreTime = new Date();
 
@@ -123,7 +124,7 @@ let PageThumbs = {
       }
 
       // Get a writeable cache entry.
-      PageThumbsCache.getWriteEntry(aBrowser.currentURI.spec, function (aEntry) {
+      PageThumbsCache.getWriteEntry(url, function (aEntry) {
         if (!aEntry) {
           finish(false);
           return;