Ensure `about:` frames use proper origin

Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/688

`about:` frames need to lookup and use the inherited
origin from their parent browsing context for proper
lookup of cosmetic filters.

src/js/contentscript.js

@@ -118,6 +118,26 @@ vAPI.contentScript = true;
 /******************************************************************************/
 /******************************************************************************/
 
+// https://github.com/uBlockOrigin/uBlock-issues/issues/688#issuecomment-663657508
+{
+    let location = self.location;
+    if ( location.protocol === 'about:' ) {
+        try {
+            let context = self;
+            do {
+                context = context.parent;
+                location = context.location;
+            } while ( context !== self.top && location.protocol === 'about:' );
+        } catch(ex) {
+        }
+    }
+    vAPI.pageLocation = location;
+}
+
+/******************************************************************************/
+/******************************************************************************/
+/******************************************************************************/
+
 vAPI.userStylesheet = {
     added: new Set(),
     removed: new Set(),
@@ -1765,8 +1785,8 @@ vAPI.injectScriptlet = function(doc, text) {
     vAPI.bootstrap = function() {
         vAPI.messaging.send('contentscript', {
             what: 'retrieveContentScriptParameters',
-            url: window.location.href,
-            isRootFrame: window === window.top,
+            url: vAPI.pageLocation.href,
+            isRootFrame: self === self.top,
             charset: document.characterSet,
         }).then(response => {
             bootstrapPhase1(response);

src/js/messaging.js

@@ -524,11 +524,15 @@ const µb = µBlock;
 
 const retrieveContentScriptParameters = function(senderDetails, request) {
     if ( µb.readyToFilter !== true ) { return; }
-    const { url, tabId, frameId } = senderDetails;
-    if ( url === undefined || tabId === undefined || frameId === undefined ) {
+    const { url: senderURL, tabId, frameId } = senderDetails;
+    if (
+        tabId === undefined ||
+        frameId === undefined ||
+        senderURL === undefined ||
+        senderURL !== request.url && senderURL.startsWith('about:') === false
+    ) {
         return;
     }
-    if ( request.url !== url ) { return; }
     const pageStore = µb.pageStoreFromTabId(tabId);
     if ( pageStore === null || pageStore.getNetFilteringSwitch() === false ) {
         return;
@@ -714,7 +718,7 @@ const onMessage = function(request, sender, callback) {
         xhr.responseType = 'text';
         xhr.onload = function() {
             this.onload = null;
-            var i18n = {
+            const i18n = {
                 bidi_dir: document.body.getAttribute('dir'),
                 create: vAPI.i18n('pickerCreate'),
                 pick: vAPI.i18n('pickerPick'),

src/js/scriptlets/cosmetic-logger.js

@@ -211,10 +211,12 @@ const processTimer = new vAPI.SafeAnimationFrame(( ) => {
 
     if ( toLog.length === 0 ) { return; }
 
+    const location = vAPI.pageLocation || self.location;
+
     vAPI.messaging.send('scriptlets', {
         what: 'logCosmeticFilteringData',
-        frameURL: window.location.href,
-        frameHostname: window.location.hostname,
+        frameURL: location.href,
+        frameHostname: location.hostname,
         matchedSelectors: toLog,
     });
     //console.timeEnd('dom logger/scanning for matches');