Graceful degradation for missing WebExtensions APIs on Chromium.

src/bg/ChildPolicies.js

@@ -51,6 +51,10 @@
     }
   };
 
+  if (!browser.contentScripts) { // #chromium fallback
+    Scripts.register = () => {};
+  }
+
   let flatten = arr => arr.reduce((a, b) => a.concat(Array.isArray(b) ? flatten(b) : b), []);
 
   let protocolRx = /^(\w+):/i;

src/bg/RequestGuard.js

@@ -20,7 +20,10 @@ var RequestGuard = (() => {
       media: "media",
       other: "",
   };
-  const allTypes = Object.keys(policyTypesMap);
+  const allTypes = UA.isMozilla ? Object.keys(policyTypesMap)
+    : ["main_frame", "sub_frame", "stylesheet", "script", "image", "font",
+    "object", "xmlhttprequest", "ping", "csp_report", "media", "websocket", "other"];
+
   Object.assign(policyTypesMap, {"webgl": "webgl"}); // fake types
   const TabStatus = {
     map: new Map(),
@@ -254,7 +257,7 @@ var RequestGuard = (() => {
     return redirected;
   }
   const ABORT = {cancel: true}, ALLOW = {};
-  const INTERNAL_SCHEME = /^(?:chrome|resource|moz-extension|about):/;
+  const INTERNAL_SCHEME = /^(?:chrome|resource|(?:moz|chrome)-extension|about):/;
   const listeners = {
     onBeforeRequest(request) {
       try {
@@ -326,7 +329,7 @@ var RequestGuard = (() => {
             capabilities = perms.capabilities;
           } else {
             capabilities = perms.capabilities;
-            if (frameAncestors.length > 0) {
+            if (frameAncestors && frameAncestors.length > 0) {
               // cascade top document's restrictions to subframes
               let topUrl = frameAncestors.pop().url;
               let topPerms = policy.get(topUrl, topUrl).perms;

src/bg/deferWebTraffic.js

@@ -31,7 +31,7 @@ function deferWebTraffic(promiseToWaitFor, next) {
       if (type === "main_frame") {
         seenTabs.add(tabId);
       } else if (documentUrl) {
-        if (frameId !== 0) {
+        if (frameId !== 0 && request.frameAncestors) {
           documentUrl = request.frameAncestors.pop().url;
         }
         reloadTab(tabId);

src/ui/Prompts.js

@@ -7,14 +7,16 @@ var Prompts = (() => {
     async open(data) {
       promptData = data;
       this.close();
-      this.currentWindow = await browser.windows.create({
+      let options = {
         url: browser.extension.getURL("ui/prompt.html"),
         type: "panel",
-        allowScriptsToClose: true,
-      //  titlePreface: "NoScript ",
         width: data.features.width,
         height: data.features.height,
-      });
+      };
+      if (UA.isMozilla) {
+        options.allowScriptsToClose = true;
+      }
+      this.currentWindow = await browser.windows.create(options);
     }
     async close() {
       if (this.currentWindow) {