Issue 6507 - Inject style sheet proactively from background page

lib/cssInjection.js

Index: lib/cssInjection.js
===================================================================
--- a/lib/cssInjection.js
+++ b/lib/cssInjection.js
@@ -152,57 +152,93 @@
   // style sheet now.
   if (oldStyleSheet && oldStyleSheet != styleSheet)
     removeStyleSheet(tabId, frameId, oldStyleSheet);
 
   frame.injectedStyleSheets.set(groupName, styleSheet);
   return true;
 }
 
-port.on("elemhide.getSelectors", (message, sender) =>
+function doElementHiding(page, frame)
 {
   let selectors = [];
   let emulatedPatterns = [];
-  let trace = devtools && devtools.hasPanel(sender.page);
+  let trace = devtools && devtools.hasPanel(page);
   let inline = !userStyleSheetsSupported;
 
-  if (!checkWhitelisted(sender.page, sender.frame,
+  if (!checkWhitelisted(page, frame,
                         RegExpFilter.typeMap.DOCUMENT |
                         RegExpFilter.typeMap.ELEMHIDE))
   {
-    let hostname = extractHostFromFrame(sender.frame);
-    let specificOnly = checkWhitelisted(sender.page, sender.frame,
+    let hostname = extractHostFromFrame(frame);
+    let specificOnly = checkWhitelisted(page, frame,
                                         RegExpFilter.typeMap.GENERICHIDE);
 
     selectors = ElemHide.getSelectorsForDomain(
       hostname,
       specificOnly ? ElemHide.SPECIFIC_ONLY : ElemHide.ALL_MATCHING
     );
 
     for (let filter of ElemHideEmulation.getRulesForDomain(hostname))
       emulatedPatterns.push({selector: filter.selector, text: filter.text});
   }
 
-  if (!inline && !updateFrameStyles(sender.page.id, sender.frame.id,
+  if (!inline && !updateFrameStyles(page.id, frame.id,
                                     selectors, "standard"))
   {
     inline = true;
   }
 
-  let response = {trace, inline, emulatedPatterns};
+  let message = {type: "elemhide.apply", trace, inline};
   if (trace || inline)
-    response.selectors = selectors;
+    message.selectors = selectors;
+
+  if (emulatedPatterns.length > 0)
+    message.emulatedPatterns = emulatedPatterns;
 
   // If we can't remove user style sheets using tabs.removeCSS, we'll only keep
   // adding them, which could cause problems with emulation filters as
   // described in issue #5864. Instead, we can just ask the content script to
   // add styles for emulation filters inline.
   if (!styleSheetRemovalSupported)
-    response.inlineEmulated = true;
+    message.inlineEmulated = true;
+
+  // In most cases on modern browsers there's nothing for the content script to
+  // do.
+  if (!message.selectors && !message.emulatedPatterns)
+    return;
 
-  return response;
+  // The content script is loaded at about the same time as we get the
+  // webNavigation.onCommitted event; sometimes we have to retry a couple of
+  // times before we get through.
+  browser.tabs.sendMessage(page.id, message, {frameId: frame.id})
+  .catch(() =>
+    browser.tabs.sendMessage(page.id, message, {frameId: frame.id})
+  )
+  .catch(() =>
+    browser.tabs.sendMessage(page.id, message, {frameId: frame.id})
+  );
+}
+
+browser.webNavigation.onCommitted.addListener(details =>
+{
+  if (!/^(https?:\/\/|about:blank\b|about:srcdoc\b)/.test(details.url))
+    return;
+
+  let page = new ext.Page({id: details.tabId, url: details.url});
+  let frame = ext.getFrame(details.tabId, details.frameId);
+
+  if (!frame)
+    return;
+
+  doElementHiding(page, frame);
+});
+
+port.on("elemhide.needApply", (message, sender) =>
+{
+  doElementHiding(sender.page, sender.frame);
 });
 
 port.on("elemhide.injectSelectors", (message, sender) =>
 {
   updateFrameStyles(sender.page.id, sender.frame.id, message.selectors,
                     message.groupName);
 });