Fixed "Hide placeholders of blocked elements" feature

webrequest.js

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
 chrome.webRequest.onBeforeRequest.addListener(onBeforeRequest, {urls: ["http://*/*", "https://*/*"]}, ["blocking"]);
 chrome.webRequest.onHeadersReceived.addListener(onHeadersReceived, {urls: ["http://*/*", "https://*/*"]}, ["responseHeaders"]);
 chrome.tabs.onRemoved.addListener(forgetTab);
 
@@ skipping 13 matching lines @@
 
   // Type names match Mozilla's with main_frame and sub_frame being the only exceptions.
   if (type == "sub_frame")
     type = "SUBDOCUMENT";
   else
     type = type.toUpperCase();
 
   var frame = (type != "SUBDOCUMENT" ? details.frameId : details.parentFrameId);
   var filter = checkRequest(type, details.tabId, details.url, frame);
   if (filter instanceof BlockingFilter)
-  {
-    var collapse = filter.collapse;
-    if (collapse == null)
-      collapse = (localStorage["hidePlaceholders"] != "false");
-    if (collapse && type == "SUBDOCUMENT")
-      return {redirectUrl: "about:blank"};
-    else if (collapse && type == "IMAGE")
-      return {redirectUrl: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAACklEQVR4nGMAAQAABQABDQottAAAAABJRU5ErkJggg=="};
-    else
-      return {cancel: true};
-  }
+    return {cancel: true};
   else
     return {};
 }
 
 function onHeadersReceived(details)
 {
   if (details.tabId == -1)
     return;
 
   var type = details.type;
@@ skipping 79 matching lines @@
   if (isFrameWhitelisted(tabId, frameId))
     return false;
 
   var documentUrl = getFrameUrl(tabId, frameId);
   if (!documentUrl)
     return false;
 
   var requestHost = extractHostFromURL(url);
   var documentHost = extractHostFromURL(documentUrl);
   var thirdParty = isThirdParty(requestHost, documentHost);
-  return defaultMatcher.matchesAny(url, type, documentHost, thirdParty);
+  var filter = defaultMatcher.matchesAny(url, type, documentHost, thirdParty);
+
+  if (filter instanceof BlockingFilter)
+  {
+    var collapse = filter.collapse;
+    if (collapse == null)
+      collapse = (localStorage["hidePlaceholders"] != "false");
+    if (collapse && (type == "SUBDOCUMENT" || type == "IMAGE"))
+    {
+      chrome.tabs.sendMessage(tabId, {
+        reqtype: "hide-element",
+        type: type,
+        url: url,
+        documentUrl: documentUrl
+      });
+    }
+  }
+
+  return filter;
 }
 
 function isFrameWhitelisted(tabId, frameId, type)
 {
   var parent = frameId;
   while (parent != -1)
   {
     var parentUrl = getFrameUrl(tabId, parent);
     if (parentUrl && isWhitelisted(parentUrl, type))
       return true;
     if (parentUrl && "keyException" in frames[tabId][frameId])
       return true;
     parent = getFrameParent(tabId, parent);
   }
   return false;
 }