Issue 521- Inject our stylesheet on per-site basis rather than globally

lib/elemHide.js

Index: lib/elemHide.js
===================================================================
--- a/lib/elemHide.js
+++ b/lib/elemHide.js
@@ -19,16 +19,17 @@
  * @fileOverview Element hiding implementation.
  */
 
 Cu.import("resource://gre/modules/Services.jsm");
 
 let {Utils} = require("utils");
 let {IO} = require("io");
 let {Prefs} = require("prefs");
+let {Policy} = require("contentPolicy");
 let {ElemHideException} = require("filterClasses");
 let {FilterNotifier} = require("filterNotifier");
 let {AboutHandler} = require("elemHideHitRegistration");
 let {TimeLine} = require("timeline");
 
 /**
  * Lookup table, filters by their associated key
  * @type Object
@@ -61,64 +62,74 @@ let styleURL = null;
 
 /**
  * Element hiding component
  * @class
  */
 let ElemHide = exports.ElemHide =
 {
   /**
-   * Indicates whether filters have been added or removed since the last apply() call.
+   * Indicates whether filters have been added or removed since the last saveStylesheet() call.
    * @type Boolean
    */
   isDirty: false,
 
-  /**
-   * Inidicates whether the element hiding stylesheet is currently applied.
-   * @type Boolean
-   */
-  applied: false,
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
 
   /**
    * Called on module startup.
    */
   init: function()
   {
     TimeLine.enter("Entered ElemHide.init()");
-    Prefs.addListener(function(name)
-    {
-      if (name == "enabled")
-        ElemHide.apply();
-    });
+
     onShutdown.add(function()
     {
-      ElemHide.unapply();
-    });
+      Services.obs.removeObserver(this, "content-document-global-created");
+    }.bind(this));
 
     TimeLine.log("done adding prefs listener");
 
     let styleFile = IO.resolveFilePath(Prefs.data_directory);
     styleFile.append("elemhide.css");
     styleURL = Services.io.newFileURI(styleFile).QueryInterface(Ci.nsIFileURL);
     TimeLine.log("done determining stylesheet URL");
 
+    Services.obs.addObserver(this, "content-document-global-created", true);
+
     TimeLine.leave("ElemHide.init() done");
   },
 
   /**
    * Removes all known filters
    */
   clear: function()
   {
     filterByKey = {__proto__: null};
     keyByFilter = {__proto__: null};
     knownExceptions = {__proto__: null};
     exceptions = {__proto__: null};
     ElemHide.isDirty = false;
-    ElemHide.unapply();
+  },
+
+  observe: function (subject, topic, data, additional)
+  {
+    if (topic != "content-document-global-created")
+      return;
+
+    if (!Prefs.enabled)
+      return;
+
+    let process = Policy.processWindow(subject, Policy.type.ELEMHIDE);
+    dump(subject.document.documentURIObject.spec + " is okay " +  process + "\n");
+    if (process)
+      return;
+
+    var windowUtils = subject.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
+    windowUtils.loadSheet(styleURL, Ci.nsIStyleSheetService.USER_SHEET);
   },
 
   /**
    * Add a new element hiding filter
    * @param {ElemHideFilter} filter
    */
   add: function(filter)
   {
@@ -191,119 +202,102 @@ let ElemHide = exports.ElemHide =
     let list = exceptions[filter.selector];
     for (let i = list.length - 1; i >= 0; i--)
       if (list[i].isActiveOnDomain(docDomain))
         return list[i];
 
     return null;
   },
 
+  shouldAllowLoad: function(wnd, filter)
+  {
+    let uri = wnd.document.documentURIObject;
+    if (!uri)
+      return true;
+
+    let domain = uri.host;
+    if (!filter.isActiveOnDomain(domain))
+      return true;
+
+    let exception = ElemHide.getException(filter, domain);
+    if (exception)
+    {
+      // FilterStorage.increaseHitCount(exception, wnd);
+      // RequestNotifier.addNodeData(node, topWnd, contentType, domain, thirdParty, locationText, exception);
+      return true;
+    }
+
+    // RequestNotifier.addNodeData(node, topWnd, contentType, domain, thirdParty, locationText, match);
+    // if (match)
+    //   FilterStorage.increaseHitCount(match, wnd);
+    return false;
+  },
+
   /**
-   * Will be set to true if apply() is running (reentrance protection).
+   * Will be set to true if saveStylesheet() is running (reentrance protection).
    * @type Boolean
    */
   _applying: false,
 
   /**
-   * Will be set to true if an apply() call arrives while apply() is already
-   * running (delayed execution).
+   * Will be set to true if an saveStylesheet() call arrives while saveStylesheet()
+   * is already running (delayed execution).
    * @type Boolean
    */
   _needsApply: false,
 
   /**
-   * Generates stylesheet URL and applies it globally
+   * Generates stylesheet URL.
    */
-  apply: function()
+  saveStylesheet: function()
   {
     if (this._applying)
     {
       this._needsApply = true;
       return;
     }
 
-    TimeLine.enter("Entered ElemHide.apply()");
-
-    if (!ElemHide.isDirty || !Prefs.enabled)
-    {
-      // Nothing changed, looks like we merely got enabled/disabled
-      if (Prefs.enabled && !ElemHide.applied)
-      {
-        try
-        {
-          Utils.styleService.loadAndRegisterSheet(styleURL, Ci.nsIStyleSheetService.USER_SHEET);
-          ElemHide.applied = true;
-        }
-        catch (e)
-        {
-          Cu.reportError(e);
-        }
-        TimeLine.log("Applying existing stylesheet finished");
-      }
-      else if (!Prefs.enabled && ElemHide.applied)
-      {
-        ElemHide.unapply();
-        TimeLine.log("ElemHide.unapply() finished");
-      }
-
-      TimeLine.leave("ElemHide.apply() done (no file changes)");
-      return;
-    }
+    TimeLine.enter("Entered ElemHide.saveStylesheet()");
 
     IO.writeToFile(styleURL.file, this._generateCSSContent(), function(e)
     {
-      TimeLine.enter("ElemHide.apply() write callback");
+      TimeLine.enter("ElemHide.saveStylesheet() write callback");
       this._applying = false;
 
       // _generateCSSContent is throwing NS_ERROR_NOT_AVAILABLE to indicate that
       // there are no filters. If that exception is passed through XPCOM we will
       // see a proper exception here, otherwise a number.
       let noFilters = (e == Cr.NS_ERROR_NOT_AVAILABLE || (e && e.result == Cr.NS_ERROR_NOT_AVAILABLE));
       if (noFilters)
       {
         e = null;
         IO.removeFile(styleURL.file, function(e) {});
       }
       else if (e)
+      {
         Cu.reportError(e);
+      }
 
       if (this._needsApply)
       {
         this._needsApply = false;
-        this.apply();
+        this.saveStylesheet();
       }
       else if (!e)
       {
         ElemHide.isDirty = false;
 
-        ElemHide.unapply();
-        TimeLine.log("ElemHide.unapply() finished");
-
-        if (!noFilters)
-        {
-          try
-          {
-            Utils.styleService.loadAndRegisterSheet(styleURL, Ci.nsIStyleSheetService.USER_SHEET);
-            ElemHide.applied = true;
-          }
-          catch (e)
-          {
-            Cu.reportError(e);
-          }
-          TimeLine.log("Applying stylesheet finished");
-        }
-
         FilterNotifier.triggerListeners("elemhideupdate");
       }
-      TimeLine.leave("ElemHide.apply() write callback done");
+      TimeLine.leave("ElemHide.saveStylesheet() write callback done");
     }.bind(this), "ElemHideWrite");
 
     this._applying = true;
 
-    TimeLine.leave("ElemHide.apply() done", "ElemHideWrite");
+    TimeLine.leave("ElemHide.saveStylesheet() done", "ElemHideWrite");
   },
 
   _generateCSSContent: function()
   {
     // Grouping selectors by domains
     TimeLine.log("start grouping selectors");
     let domains = {__proto__: null};
     let hasFilters = false;
@@ -352,44 +346,16 @@ let ElemHide = exports.ElemHide =
 
       for (let selector in list)
         yield selector.replace(/[^\x01-\x7F]/g, escapeChar) + "{" + cssTemplate.replace("%ID%", list[selector]) + "}";
       yield '}';
     }
   },
 
   /**
-   * Unapplies current stylesheet URL
-   */
-  unapply: function()
-  {
-    if (ElemHide.applied)
-    {
-      try
-      {
-        Utils.styleService.unregisterSheet(styleURL, Ci.nsIStyleSheetService.USER_SHEET);
-      }
-      catch (e)
-      {
-        Cu.reportError(e);
-      }
-      ElemHide.applied = false;
-    }
-  },
-
-  /**
-   * Retrieves the currently applied stylesheet URL
-   * @type String
-   */
-  get styleURL()
-  {
-    return ElemHide.applied ? styleURL.spec : null;
-  },
-
-  /**
    * Retrieves an element hiding filter by the corresponding protocol key
    */
   getFilterByKey: function(/**String*/ key) /**Filter*/
   {
     return (key in filterByKey ? filterByKey[key] : null);
   },
 
   /**