Issue 3792 - Fix to support multiprocess firefox

lib/child/frameScript.js

+"use strict";

[Wladimir Palant, 2016/03/15 10:07:10]

We put "use strict" after the license header.

[sergei, 2016/03/16 14:44:23]

Done.

+/*
+ * 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/.
+ */
+
+/**
+ * Sends exception to parent process script using "abpcrawler:reportException"
+ * message with CPOW of the exception parameter.
+ * @param e exception to be sent.
+ */
+function reportException(e)
+{
+  sendSyncMessage("abpcrawler:reportException", undefined, e);

[Wladimir Palant, 2016/03/15 10:07:10]

Don't send sync messages unless you absolutely cannot help it (no, this isn't
such a case).

[sergei, 2016/03/16 14:44:23]

Acknowledged.
JIC, it was sync here because CPOW is used (see comment in lib/crawler.js) here
and to avoid race conditions we should pass it using synchronous message.

+}
+
+const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
+
+let {Services} = Cu.import("resource://gre/modules/Services.jsm", {});
+let {XPCOMUtils} = Cu.import("resource://gre/modules/XPCOMUtils.jsm", {});
+
+/**
+ * Waits for finishing of the page loading, calls `gatherPageInfo` and sends
+ * gahter information using "abpcrawler:pageInfoGathered" message.
+ * https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIWebProgressListener
+ */
+let webProgressListener =
+{
+  onStateChange: function(webProgress, request, flags, status)
+  {
+    if ((flags & Ci.nsIWebProgressListener.STATE_STOP) && (flags & Ci.nsIWebProgressListener.STATE_IS_WINDOW))
+    {
+      if (request instanceof Ci.nsIHttpChannel)
+      {
+        let pageInfo = {headers: []};
+        try
+        {
+          pageInfo.headers.push("HTTP/x.x " + request.responseStatus + " " + request.responseStatusText);
+          request.visitResponseHeaders((header, value) =>pageInfo.headers.push(header + ": " + value));
+        }
+        catch (e)
+        {
+          reportException(e);
+        }
+        Object.assign(pageInfo, gatherPageInfo(content));
+        sendAsyncMessage("abpcrawler:pageInfoGathered", pageInfo);
+      }
+    }
+  },
+
+  // definitions of the remaining functions see related documentation
+  onLocationChange: function(webProgress, request, URI, flag) {},
+  onProgressChange: function(aWebProgress, aRequest, curSelf, maxSelf, curTot, maxTot) {},
+  onStatusChange: function(aWebProgress, aRequest, aStatus, aMessage) {},
+  onSecurityChange: function(aWebProgress, aRequest, aState) {},
+ 
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIWebProgressListener, Ci.nsISupportsWeakReference])
+};
+
+let filter = Cc["@mozilla.org/appshell/component/browser-status-filter;1"]
+             .createInstance(Ci.nsIWebProgress);
+filter.addProgressListener(webProgressListener, Ci.nsIWebProgress.NOTIFY_ALL);
+
+let webProgress = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
+                          .getInterface(Ci.nsIWebProgress);
+webProgress.addProgressListener(filter, Ci.nsIWebProgress.NOTIFY_ALL);
+
+/**
+ * Gathers information about page using 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 = {};
+  if (document.documentElement)
+  {
+    try
+    {
+      let canvas = document.createElementNS("http://www.w3.org/1999/xhtml", "canvas");
+      canvas.width = document.documentElement.scrollWidth;
+      canvas.height = document.documentElement.scrollHeight;
+      if (canvas.width > 0 && canvas.height > 0)
+      {
+        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);
+      }
+      // TODO: Capture frames as well?
+      let serializer = new wnd.XMLSerializer();
+      result.source = serializer.serializeToString(document.documentElement);
+    }
+    catch (e)
+    {
+      reportException(e);
+      result.error = "Cannot gather page info";
+    }
+  }
+  return result;
+}