Add TODO to look into localStorage detection bug

This hides "window.injectScript undefined" console errors in Chrome that
started in b7e9aea

The aforementioned commit merely made the problem more visible, however.
The underlying issue (FRAME_URL/injectScript from the utils.js content
script sometimes being undefined in the supercookie.js content script)
was already present at that point.

src/js/contentscripts/supercookie.js

@@ -119,6 +119,9 @@ if (window.top == window) {
 //
 // could then remove test workarounds like
 // https://github.com/EFForg/privacybadger/commit/39d5d0899e22d1c451d429e44553c5f9cad7fc46
+
+// TODO sometimes contentscripts/utils.js isn't here?!
+// TODO window.FRAME_URL / window.injectScript are undefined ...
 chrome.runtime.sendMessage({
   type: "checkEnabledAndThirdParty",
   frameUrl: window.FRAME_URL

src/js/webrequest.js

@@ -682,14 +682,15 @@ function dispatcher(request, sender, sendResponse) {
       return sendResponse();
     }
 
-    let requestHost = window.extractHostFromURL(request.frameUrl);
+    let frame_host = window.extractHostFromURL(request.frameUrl),
+      tab_host = window.extractHostFromURL(sender.tab.url);
 
     // Ignore requests that aren't from a third party.
-    if (!utils.isThirdPartyDomain(requestHost, window.extractHostFromURL(sender.tab.url))) {
+    if (!frame_host || !utils.isThirdPartyDomain(frame_host, tab_host)) {
       return sendResponse();
     }
 
-    let action = checkAction(sender.tab.id, requestHost);
+    let action = checkAction(sender.tab.id, frame_host);
     sendResponse(action == constants.COOKIEBLOCK || action == constants.USER_COOKIE_BLOCK);
 
     break;
@@ -770,7 +771,7 @@ function dispatcher(request, sender, sendResponse) {
   }
 
   case "supercookieReport": {
-    if (badger.hasSuperCookie(request.data)) {
+    if (request.frameUrl && badger.hasSuperCookie(request.data)) {
       recordSuperCookie(sender.tab.id, request.frameUrl);
     }
     break;
@@ -780,7 +781,9 @@ function dispatcher(request, sender, sendResponse) {
     let tab_host = window.extractHostFromURL(sender.tab.url),
       frame_host = window.extractHostFromURL(request.frameUrl);
 
-    sendResponse(badger.isPrivacyBadgerEnabled(tab_host) && utils.isThirdPartyDomain(frame_host, tab_host));
+    sendResponse(frame_host &&
+      badger.isPrivacyBadgerEnabled(tab_host) &&
+      utils.isThirdPartyDomain(frame_host, tab_host));
 
     break;
   }