this fixes #274

platform/chromium/vapi-background.js

@@ -42,13 +42,6 @@ var noopFunc = function(){};
 
 /******************************************************************************/
 
-// https://github.com/gorhill/uMatrix/issues/234
-// https://developer.chrome.com/extensions/privacy#property-network
-
-chrome.privacy.network.networkPredictionEnabled.set({ value: false });
-
-/******************************************************************************/
-
 vAPI.app = {
     name: manifest.name,
     version: manifest.version
@@ -68,6 +61,37 @@ vAPI.storage = chrome.storage.local;
 
 /******************************************************************************/
 
+// https://github.com/gorhill/uMatrix/issues/234
+// https://developer.chrome.com/extensions/privacy#property-network
+
+chrome.privacy.network.networkPredictionEnabled.set({
+    value: false,
+    scope: 'regular'
+});
+
+vAPI.browserSettings = {
+    set: function(details) {
+        for ( var setting in details ) {
+            if ( details.hasOwnProperty(setting) === false ) {
+                continue;
+            }
+            switch ( setting ) {
+            case 'prefetching':
+                chrome.privacy.network.networkPredictionEnabled.set({
+                    value: !!details[setting],
+                    scope: 'regular'
+                });
+                break;
+
+            default:
+                break;
+            }
+        }
+    }
+};
+
+/******************************************************************************/
+
 vAPI.tabs = {};
 
 /******************************************************************************/

platform/firefox/vapi-background.js

@@ -97,6 +97,26 @@ window.addEventListener('unload', function() {
 
 /******************************************************************************/
 
+vAPI.browserSettings = {
+    set: function(details) {
+        for ( var setting in details ) {
+            if ( details.hasOwnProperty(setting) === false ) {
+                continue;
+            }
+            switch ( setting ) {
+            case 'prefetching':
+                // noop until I find what to use in Firefox
+                break;
+
+            default:
+                break;
+            }
+        }
+    }
+};
+
+/******************************************************************************/
+
 // API matches that of chrome.storage.local:
 //   https://developer.chrome.com/extensions/storage
 
@@ -404,6 +424,7 @@ vAPI.tabs.registerListeners = function() {
 /******************************************************************************/
 
 // Firefox:
+//   https://developer.mozilla.org/en-US/Add-ons/Code_snippets/Tabbed_browser
 //
 // browser --> ownerDocument --> defaultView --> gBrowser --> browsers --+
 //    ^                                                                  |

src/_locales/en/messages.json

@@ -171,6 +171,10 @@
     "message":"I am an advanced user (<a href='https:\/\/github.com\/gorhill\/uBlock\/wiki\/Advanced-user-features'>Required reading<\/a>)",
     "description":"English: "
   },
+  "settingsPrefetchingDisabledPrompt":{
+    "message":"Disable pre-fetching (to prevent any connection for blocked network requests)",
+    "description":"English: "
+  },
   "settingsExperimentalPrompt":{
     "message":"Enable experimental features (<a href='https:\/\/github.com\/gorhill\/uBlock\/wiki\/Experimental-features'>About<\/a>)",
     "description":"English: Enable experimental features"

src/js/background.js

@@ -63,6 +63,7 @@ return {
         externalLists: defaultExternalLists,
         firewallPaneMinimized: true,
         parseAllABPHideFilters: true,
+        prefetchingDisabled: true,
         requestLogMaxEntries: 1000,
         showIconBadge: true
     },

src/js/settings.js

@@ -186,6 +186,12 @@ var onUserSettingsReceived = function(details) {
             changeUserSettings('colorBlindFriendly', this.checked);
         });
 
+    uDom('#prefetching-disabled')
+        .prop('checked', details.prefetchingDisabled === true)
+        .on('change', function(){
+            changeUserSettings('prefetchingDisabled', this.checked);
+        });
+
     uDom('#advanced-user-enabled')
         .prop('checked', details.advancedUserEnabled === true)
         .on('change', function(){

src/js/start.js

@@ -144,6 +144,8 @@ var onUserSettingsReady = function(fetched) {
     userSettings.experimentalEnabled = false;
 
     µb.contextMenu.toggle(userSettings.contextMenuEnabled);
+    vAPI.browserSettings.set({ 'prefetching': !userSettings.prefetchingDisabled });
+
     µb.permanentFirewall.fromString(fetched.dynamicFilteringString);
     µb.sessionFirewall.assign(µb.permanentFirewall);
     µb.permanentURLFiltering.fromString(fetched.urlFilteringString);

src/js/ublock.js

@@ -273,6 +273,11 @@ var matchWhitelistDirective = function(url, hostname, directive) {
         break;
     case 'experimentalEnabled':
         break;
+    case 'prefetchingDisabled':
+        vAPI.browserSettings.set({
+            'prefetching': !value
+        });
+        break;
     default:
         break;
     }

src/settings.html

@@ -17,6 +17,7 @@
     <li><input id="color-blind-friendly" type="checkbox"><label data-i18n="settingsColorBlindPrompt" for="color-blind-friendly"></label>
     <li><input id="advanced-user-enabled" type="checkbox"><label data-i18n="settingsAdvancedUserPrompt" for="advanced-user-enabled"></label>
     <!-- <li><input id="experimental-enabled" type="checkbox" disabled><label data-i18n="settingsExperimentalPrompt" for="experimental-enabled"></label> -->
+    <li><input id="prefetching-disabled" type="checkbox"><label data-i18n="settingsPrefetchingDisabledPrompt" for="prefetching-disabled"></label>
     </ul>
 
 <div id="localData" style="margin: 0 1em;">