Issue 3792 - Fix to support multiprocess firefox

lib/child/frameScript.js

Index: lib/child/frameScript.js
===================================================================
new file mode 100644
--- /dev/null
+++ b/lib/child/frameScript.js
@@ -0,0 +1,129 @@
+/*
+ * 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/.
+ */
+
+"use strict";
+
+const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
+
+/**
+ * @param e exception
+ */
+function reportException(e)
+{
+  let stack = "";
+  if (e && typeof e == "object" && "stack" in e)
+    stack = e.stack + "\n";
+
+  Cu.reportError(e);
+  dump(e + "\n" + stack + "\n");
+}
+
+const {XPCOMUtils} = Cu.import("resource://gre/modules/XPCOMUtils.jsm", {});
+
+/**
+ * Progress listener capturing the data of the current page and calling
+ * onPageLoaded(data) when loading is finished, where data contains
+ * HTTP status and headers.
+ *
+ * @type nsIWebProgressListener
+ */
+let webProgressListener =
+{
+  onStateChange: function(webProgress, request, flags, status)
+  {
+    if (webProgress.DOMWindow == content &&
+        (flags & Ci.nsIWebProgressListener.STATE_STOP))
+    {
+      // First time we receive STATE_STOP for about:blank and the second time
+      // for our interested URL which is distinct from about:blank.
+      // However we should not process about:blank because it can happen that
+      // the message with information about about:blank is delivered when the
+      // code in crawler.js is already waiting for a message from this tab.
+      // Another case we are not interested in is about:newtab.
+      if (content.location.protocol == "about:")
+        return;
+      let pageInfo = {channelStatus: status};
+      if (request instanceof Ci.nsIHttpChannel)
+      {
+        try
+        {
+          pageInfo.headers = [];
+          pageInfo.headers.push("HTTP/x.x " + request.responseStatus + " " + request.responseStatusText);
+          request.visitResponseHeaders((header, value) => pageInfo.headers.push(header + ": " + value));
+        }
+        catch (e)
+        {
+          reportException(e);
+        }
+      }
+      onPageLoaded(pageInfo);
+    }
+  },
+
+  onLocationChange: function() {},
+  onProgressChange: function() {},
+  onStatusChange: function() {},
+  onSecurityChange: function() {},
+
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIWebProgressListener, Ci.nsISupportsWeakReference])
+};
+
+function onPageLoaded(pageInfo)
+{
+  Object.assign(pageInfo, gatherPageInfo(content));
+  sendAsyncMessage("abpcrawler:pageInfoGathered", pageInfo);
+};
+
+let webProgress = docShell.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIWebProgress);
+webProgress.addProgressListener(webProgressListener, Ci.nsIWebProgress.NOTIFY_STATE_WINDOW);
+
+/**
+ * Gathers information about a DOM window.
+ * Currently
+ *  - creates a screenshot of the page
+ *  - serializes the page source code
+ * @param {nsIDOMWindow} wnd window to process
+ * @return {Object} the object containing "screenshot" and "source" properties.
+ */
+function gatherPageInfo(wnd)
+{
+  let document = wnd.document;
+  let result = {errors:[]};
+  if (!document.documentElement)
+  {
+    result.errors.push("No document.documentElement");
+    return result;
+  }
+
+  try
+  {
+    let canvas = document.createElementNS("http://www.w3.org/1999/xhtml", "canvas");
+    canvas.width = document.documentElement.scrollWidth;
+    canvas.height = document.documentElement.scrollHeight;
+    let context = canvas.getContext("2d");
+    context.drawWindow(wnd, 0, 0, canvas.width, canvas.height, "rgb(255, 255, 255)");
+    result.screenshot = canvas.toDataURL("image/jpeg", 0.8);
+  }
+  catch (e)
+  {
+    reportException(e);
+    result.errors.push("Cannot make page screenshot");
+  }
+
+  try
+  {
+    // TODO: Capture frames as well?
+    let serializer = new wnd.XMLSerializer();
+    result.source = serializer.serializeToString(document.documentElement);
+  }
+  catch(e)
+  {
+    reportException(e);
+    result.errors.push("Cannot obtain page source code");
+  }
+
+  return result;
+}