Rework behavior of "Suspend network activity until ..."

The setting will default to the natural capability of the browser:

- Checked for Firefox
- Unchecked for Chromium-based browsers

For Chromium-based browser, if checked, network requests will be
redirected to an empty resources instead of blocking the
connection.

Related feedback:
- https://github.com/uBlockOrigin/uBlock-issues/issues/1973
- https://www.reddit.com/r/uBlockOrigin/comments/squo8n/latest_update_blocks_network_connections_at/

platform/chromium/vapi-background-ext.js

@@ -183,7 +183,9 @@ vAPI.Tabs = class extends vAPI.Tabs {
 
         suspendOneRequest(details) {
             this.suspendedTabIds.add(details.tabId);
-            return { cancel: true };
+            return {
+                redirectUrl: vAPI.getURL(`web_accessible_resources/empty?secret=${vAPI.warSecret()}`)
+            };
         }
 
         unsuspendAllRequests(discard = false) {

platform/common/vapi-background.js

@@ -1249,7 +1249,7 @@ vAPI.Net = class {
         if ( this.suspendDepth !== 0 ) { return; }
         this.unsuspendAllRequests(discard);
     }
-    canSuspend() {
+    static canSuspend() {
         return false;
     }
 };

platform/firefox/vapi-background-ext.js

@@ -303,7 +303,7 @@ import {
                 );
             }
         }
-        canSuspend() {
+        static canSuspend() {
             return true;
         }
     };

src/js/background.js

@@ -110,7 +110,7 @@ const userSettingsDefault = {
     prefetchingDisabled: true,
     requestLogMaxEntries: 1000,
     showIconBadge: true,
-    suspendUntilListsAreLoaded: true,
+    suspendUntilListsAreLoaded: vAPI.Net.canSuspend(),
     tooltipsDisabled: false,
     webrtcIPAddressHidden: false,
 };

src/js/start.js

@@ -201,10 +201,20 @@ const onNetWhitelistReady = function(netWhitelistRaw, adminExtra) {
 
 const onUserSettingsReady = function(fetched) {
     // Terminate suspended state?
-    if ( fetched.suspendUntilListsAreLoaded === false ) {
+    const tnow = Date.now() - vAPI.T0;
+    if (
+        vAPI.Net.canSuspend() &&
+        fetched.suspendUntilListsAreLoaded === false
+    ) {
         vAPI.net.unsuspend({ all: true, discard: true });
-        ubolog(`Unsuspend network activity listener`);
+        ubolog(`Unsuspend network activity listener at ${tnow} ms`);
-        µb.supportStats.unsuspendAfter = `${Date.now() - vAPI.T0} ms`;
+        µb.supportStats.unsuspendAfter = `${tnow} ms`;
+    } else if (
+        vAPI.Net.canSuspend() === false &&
+        fetched.suspendUntilListsAreLoaded
+    ) {
+        vAPI.net.suspend();
+        ubolog(`Suspend network activity listener at ${tnow} ms`);
     }
 
     // `externalLists` will be deprecated in some future, it is kept around

src/js/storage.js

@@ -805,7 +805,7 @@ self.addEventListener('hiddenSettingsChanged', ( ) => {
     const onFilterListsReady = function(lists) {
         this.availableFilterLists = lists;
 
-        if ( vAPI.net.canSuspend() ) {
+        if ( vAPI.Net.canSuspend() ) {
             vAPI.net.suspend();
         }
         redirectEngine.reset();

src/js/traffic.js

@@ -1136,7 +1136,9 @@ const webRequest = {
 
     start: (( ) => {
         vAPI.net = new vAPI.Net();
-        vAPI.net.suspend();
+        if ( vAPI.Net.canSuspend() ) {
+            vAPI.net.suspend();
+        }
 
         return async ( ) => {
             vAPI.net.setSuspendableListener(onBeforeRequest);