Issue 370 - Right-clicked element is removed independent of created filter

safari/ext/background.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
- * Copyright (C) 2006-2013 Eyeo GmbH
+ * Copyright (C) 2006-2014 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 (function()
 {
-  /* Tabs */
-
-  var TabEventTarget = function()
-  {
-    WrappedEventTarget.apply(this, arguments);
-  };
-  TabEventTarget.prototype = {
-    __proto__: WrappedEventTarget.prototype,
-    _wrapListener: function(listener)
-    {
-      return function(event)
+  /* Pages */
+
+  var pages = {__proto__: null};
+  var pageCounter = 0;
+
+  var Page = function(id, tab, url)
+  {
+    this._id = id;
+    this._tab = tab;
+    this._frames = [{url: url, parent: null}];
+
+    if (tab.page)
+      this._messageProxy = new ext._MessageProxy(tab.page);
+    else
+      // while the new tab page is shown on Safari 7, the 'page' property
+      // of the tab is undefined, and we can't send messages to that page
+      this._messageProxy = {
+        handleRequest: function() {},
+        handleResponse: function() {},
+        sendMessage: function() {}
+      };
+
+    this.browserAction = new BrowserAction(this);
+    this.contextMenus = new ContextMenus(this);
+  };
+  Page.prototype = {
+    get url()
+    {
+      return this._frames[0].url;
+    },
+    activate: function()
+    {
+      this._tab.activate();
+    },
+    sendMessage: function(message, responseCallback)
+    {
+      this._messageProxy.sendMessage(message, responseCallback, {pageId: this._id});
+    }
+  };
+
+  var isPageActive = function(page)
+  {
+    var tab = page._tab;
+    return tab == tab.browserWindow.activeTab && page == tab._visiblePage;
+  };
+
+  var forgetPage = function(id)
+  {
+    ext._removeFromAllPageMaps(id);
+
+    delete pages[id]._tab._pages[id];
+    delete pages[id];
+  };
+
+  var replacePage = function(page)
+  {
+    var tab = page._tab;
+    tab._visiblePage = page;
+
+    for (var id in tab._pages)
+    {
+      if (id != page._id)
+        forgetPage(id);
+    }
+
+    if (isPageActive(page))
+      updateToolbarItemForPage(page, tab.browserWindow);
+  };
+
+  ext.pages = {
+    open: function(url, callback)
+    {
+      var tab = safari.application.activeBrowserWindow.openTab();
+      tab.url = url;
+
+      if (callback)
       {
-        if (event.target instanceof SafariBrowserTab)
-          listener(new Tab(event.target));
-      };
-    }
-  };
-
-  var LoadingTabEventTarget = function(target)
-  {
-    WrappedEventTarget.call(this, target, "message", false);
-  };
-  LoadingTabEventTarget.prototype = {
-    __proto__: WrappedEventTarget.prototype,
-    _wrapListener: function(listener)
-    {
-      return function (event)
-      {
-        if (event.name == "loading" && event.message == event.target.url)
-          listener(new Tab(event.target));
-      };
-    }
-  };
-
-  Tab = function(tab)
-  {
-    this._tab = tab;
-
-    this._eventTarget = tab;
-    this._messageDispatcher = tab.page;
-
-    this.onLoading = new LoadingTabEventTarget(tab);
-    this.onCompleted = new TabEventTarget(tab, "navigate", false);
-    this.onActivated = new TabEventTarget(tab, "activate", false);
-    this.onRemoved = new TabEventTarget(tab, "close", false);
-  };
-  Tab.prototype = {
-    get url()
-    {
-      return this._tab.url;
-    },
-    close: function()
-    {
-      this._tab.close();
-    },
-    activate: function()
-    {
-      this._tab.activate();
-    },
-    sendMessage: sendMessage,
-    browserAction: {
-      setIcon: function(path)
-      {
-        safari.extension.toolbarItems[0].image = safari.extension.baseURI + path;
-      },
-      setTitle: function(title)
-      {
-        safari.extension.toolbarItems[0].toolTip = title;
-      },
-      setBadge: function(badge)
-      {
-        if (!badge)
-          safari.extension.toolbarItems[0].badge = 0;
-        else if ("number" in badge)
-          safari.extension.toolbarItems[0].badge = badge.number;
-      }
-    }
-  };
-
-  TabMap = function()
-  {
-    this._tabs = [];
-    this._values = [];
-
-    this._onClosed = this._onClosed.bind(this);
-  };
-  TabMap.prototype =
-  {
-    get: function(tab) {
-      var idx;
-
-      if (!tab || (idx = this._tabs.indexOf(tab._tab)) == -1)
-        return null;
-
-      return this._values[idx];
-    },
-    set: function(tab, value)
-    {
-      var idx = this._tabs.indexOf(tab._tab);
-
-      if (idx != -1)
-        this._values[idx] = value;
-      else
-      {
-        this._tabs.push(tab._tab);
-        this._values.push(value);
-
-        tab._tab.addEventListener("close", this._onClosed, false);
-      }
-    },
-    has: function(tab)
-    {
-      return this._tabs.indexOf(tab._tab) != -1;
-    },
-    clear: function()
-    {
-      while (this._tabs.length > 0)
-        this._delete(this._tabs[0]);
-    },
-    _delete: function(tab)
-    {
-      var idx = this._tabs.indexOf(tab);
-
-      if (idx != -1)
-      {
-        this._tabs.splice(idx, 1);
-        this._values.splice(idx, 1);
-
-        tab.removeEventListener("close", this._onClosed, false);
-      }
-    },
-    _onClosed: function(event)
-    {
-      this._delete(event.target);
-    }
-  };
-  TabMap.prototype["delete"] = function(tab)
-  {
-    this._delete(tab._tab);
-  };
-
-
-  /* Windows */
-
-  Window = function(win)
-  {
-    this._win = win;
-  }
-  Window.prototype = {
-    get visible()
-    {
-      return this._win.visible;
-    },
-    getAllTabs: function(callback)
-    {
-      callback(this._win.tabs.map(function(tab) { return new Tab(tab); }));
-    },
-    getActiveTab: function(callback)
-    {
-      callback(new Tab(this._win.activeTab));
-    },
-    openTab: function(url, callback)
-    {
-      var tab = this._win.openTab();
-      tab.url = url;
-
-      if (callback)
-        callback(new Tab(tab));
-    }
-  };
-
-  if (safari.extension.globalPage.contentWindow == window)
-  {
-    /* Background page proxy */
-
-    var proxy = {
-      tabs: [],
-      objects: [],
-
-      registerObject: function(obj, objects)
-      {
-        var objectId = objects.indexOf(obj);
-
-        if (objectId == -1)
-          objectId = objects.push(obj) - 1;
-
-        return objectId;
-      },
-      serializeSequence: function(sequence, objects, memo)
-      {
-        if (!memo)
-          memo = {specs: [], arrays: []};
-
-        var items = [];
-        for (var i = 0; i < sequence.length; i++)
-          items.push(this.serialize(sequence[i], objects, memo));
-
-        return items;
-      },
-      serialize: function(obj, objects, memo)
-      {
-        if (typeof obj == "object" && obj != null || typeof obj == "function")
+        var onLoading = function(page)
         {
-          if (obj.constructor == Array)
-          {
-            if (!memo)
-              memo = {specs: [], arrays: []};
-
-            var idx = memo.arrays.indexOf(obj);
-            if (idx != -1)
-              return memo.specs[idx];
-
-            var spec = {type: "array"};
-            memo.specs.push(spec);
-            memo.arrays.push(obj);
-
-            spec.items = this.serializeSequence(obj, objects, memo);
-            return spec;
-          }
-
-          if (obj.constructor != Date && obj.constructor != RegExp)
-            return {type: "object", objectId: this.registerObject(obj, objects)};
-        }
-
-        return {type: "value", value: obj};
-      },
-      createCallback: function(callbackId, tab)
-      {
-        var proxy = this;
-
-        return function()
-        {
-          var idx = proxy.tabs.indexOf(tab);
-
-          if (idx != -1) {
-            var objects = proxy.objects[idx];
-
-            tab.page.dispatchMessage("proxyCallback",
-            {
-              callbackId: callbackId,
-              contextId: proxy.registerObject(this, objects),
-              args: proxy.serializeSequence(arguments, objects)
-            });
+          if (page._tab == tab)
+          {
+            ext.pages.onLoading.removeListener(onLoading);
+            callback(page);
           }
         };
-      },
-      deserialize: function(spec, objects, tab, memo)
+        ext.pages.onLoading.addListener(onLoading);
+      }
+    },
+    query: function(info, callback)
+    {
+      var matchedPages = [];
+
+      for (var id in pages)
       {
-        switch (spec.type)
+        var page = pages[id];
+        var win = page._tab.browserWindow;
+
+        if ("active" in info && info.active != isPageActive(page))
+          continue;
+        if ("lastFocusedWindow" in info && info.lastFocusedWindow != (win == safari.application.activeBrowserWindow))
+          continue;
+
+        matchedPages.push(page);
+      };
+
+      callback(matchedPages);
+    },
+    onLoading: new ext._EventTarget()
+  };
+
+  safari.application.addEventListener("close", function(event)
+  {
+    // this event is dispatched on closing windows and tabs. However when a
+    // window is closed, it is first dispatched on each tab in the window and
+    // then on the window itself. But we are only interested in closed tabs.
+    if (!(event.target instanceof SafariBrowserTab))
+      return;
+
+    // when a tab is closed, forget the previous page associated with that
+    // tab. Note that it wouldn't be sufficient do that when the old page
+    // is unloading, because Safari dispatches window.onunload only when
+    // reloading the page or following links, but not when closing the tab.
+    for (var id in event.target._pages)
+      forgetPage(id);
+  }, true);
+
+
+  /* Browser actions */
+
+  var toolbarItemProperties = {};
+
+  var getToolbarItemForWindow = function(win)
+  {
+    for (var i = 0; i < safari.extension.toolbarItems.length; i++)
+    {
+      var toolbarItem = safari.extension.toolbarItems[i];
+
+      if (toolbarItem.browserWindow == win)
+        return toolbarItem;
+    }
+
+    return null;
+  };
+
+  var updateToolbarItemForPage = function(page, win) {
+    var toolbarItem = getToolbarItemForWindow(win);
+    if (!toolbarItem)
+      return;
+
+    for (var name in toolbarItemProperties)
+    {
+      var property = toolbarItemProperties[name];
+
+      if (page && property.pages.has(page))
+        toolbarItem[name] = property.pages.get(page);
+      else
+        toolbarItem[name] = property.global;
+    }
+  };
+
+  var BrowserAction = function(page)
+  {
+    this._page = page;
+  };
+  BrowserAction.prototype = {
+    _set: function(name, value)
+    {
+      var toolbarItem = getToolbarItemForWindow(this._page._tab.browserWindow);
+      if (!toolbarItem)
+        return;
+
+      var property = toolbarItemProperties[name];
+      if (!property)
+        property = toolbarItemProperties[name] = {
+          pages: new ext.PageMap(),
+          global: toolbarItem[name]
+        };
+
+      property.pages.set(this._page, value);
+
+      if (isPageActive(this._page))
+        toolbarItem[name] = value;
+    },
+    setIcon: function(path)
+    {
+      this._set("image", safari.extension.baseURI + path.replace("$size", "16"));
+    },
+    setBadge: function(badge)
+    {
+      if (!badge)
+        this._set("badge", 0);
+      else if ("number" in badge)
+        this._set("badge", badge.number);
+    }
+  };
+
+  safari.application.addEventListener("activate", function(event)
+  {
+    // this event is also dispatched on windows that got focused. But we
+    // are only interested in tabs, which became active in their window.
+    if (!(event.target instanceof SafariBrowserTab))
+      return;
+
+    // update the toolbar item for the page visible in the tab that just
+    // became active. If we can't find that page (e.g. when a page was
+    // opened in a new tab, and our content script didn't run yet), the
+    // toolbar item of the window, is reset to its intial configuration.
+    updateToolbarItemForPage(event.target._visiblePage, event.target.browserWindow);
+  }, true);
+
+
+  /* Context menus */
+
+  var contextMenuItems = new ext.PageMap();
+
+  var ContextMenus = function(page)
+  {
+    this._page = page;
+  };
+  ContextMenus.prototype = {
+    create: function(item)
+    {
+      var items = contextMenuItems.get(this._page);
+      if (!items)
+        contextMenuItems.set(this._page, items = []);
+
+      items.push(item);
+    },
+    removeAll: function()
+    {
+      contextMenuItems.delete(this._page);
+    }
+  };
+
+  safari.application.addEventListener("contextmenu", function(event)
+  {
+    var pageId = event.userInfo.pageId;
+    if (!pageId)
+      return;
+
+    var page = pages[event.userInfo.pageId];
+    var items = contextMenuItems.get(page);
+    if (!items)
+      return;
+
+    var context = event.userInfo.tagName;
+    if (context == "img")
+      context = "image";
+    if (!event.userInfo.srcUrl)
+      context = null;
+
+    for (var i = 0; i < items.length; i++)
+    {
+      // Supported contexts are: all, audio, image, video
+      var menuItem = items[i];
+      if (menuItem.contexts.indexOf("all") == -1 && menuItem.contexts.indexOf(context) == -1)
+        continue;
+
+      event.contextMenu.appendContextMenuItem(i, menuItem.title);
+    }
+  });
+
+  safari.application.addEventListener("command", function(event)
+  {
+    var page = pages[event.userInfo.pageId];
+    var items = contextMenuItems.get(page);
+
+    items[event.command].onclick(event.userInfo.srcUrl, page);
+  });
+
+
+  /* Web requests */
+
+  ext.webRequest = {
+    onBeforeRequest: new ext._EventTarget(true),
+    handlerBehaviorChanged: function() {}
+  };
+
+
+  /* Background page */
+
+  ext.backgroundPage = {
+    getWindow: function()
+    {
+      return window;
+    }
+  };
+
+
+  /* Background page proxy (for access from content scripts) */
+
+  var backgroundPageProxy = {
+    cache: new ext.PageMap(),
+
+    registerObject: function(obj, objects)
+    {
+      var objectId = objects.indexOf(obj);
+
+      if (objectId == -1)
+        objectId = objects.push(obj) - 1;
+
+      return objectId;
+    },
+    serializeSequence: function(sequence, objects, memo)
+    {
+      if (!memo)
+        memo = {specs: [], arrays: []};
+
+      var items = [];
+      for (var i = 0; i < sequence.length; i++)
+        items.push(this.serialize(sequence[i], objects, memo));
+
+      return items;
+    },
+    serialize: function(obj, objects, memo)
+    {
+      if (typeof obj == "object" && obj != null || typeof obj == "function")
+      {
+        if (obj.constructor == Array)
         {
-          case "value":
-            return spec.value;
-          case "hosted":
-            return objects[spec.objectId];
-          case "callback":
-            return this.createCallback(spec.callbackId, tab);
-          case "object":
-          case "array":
-            if (!memo)
-              memo = {specs: [], objects: []};
-
-            var idx = memo.specs.indexOf(spec);
-            if (idx != -1)
-              return memo.objects[idx];
-
-            var obj;
-            if (spec.type == "array")
-              obj = [];
+          if (!memo)
+            memo = {specs: [], arrays: []};
+
+          var idx = memo.arrays.indexOf(obj);
+          if (idx != -1)
+            return memo.specs[idx];
+
+          var spec = {type: "array"};
+          memo.specs.push(spec);
+          memo.arrays.push(obj);
+
+          spec.items = this.serializeSequence(obj, objects, memo);
+          return spec;
+        }
+
+        if (obj.constructor != Date && obj.constructor != RegExp)
+          return {type: "object", objectId: this.registerObject(obj, objects)};
+      }
+
+      return {type: "value", value: obj};
+    },
+    createCallback: function(callbackId, pageId, frameId)
+    {
+      var proxy = this;
+
+      return function()
+      {
+        var page = pages[pageId];
+        if (!page)
+          return;
+
+        var objects = proxy.cache.get(page);
+        if (!objects)
+          return;
+
+        page._tab.page.dispatchMessage("proxyCallback",
+        {
+          pageId: pageId,
+          frameId: frameId,
+          callbackId: callbackId,
+          contextId: proxy.registerObject(this, objects),
+          args: proxy.serializeSequence(arguments, objects)
+        });
+      };
+    },
+    deserialize: function(spec, objects, pageId, memo)
+    {
+      switch (spec.type)
+      {
+        case "value":
+          return spec.value;
+        case "hosted":
+          return objects[spec.objectId];
+        case "callback":
+          return this.createCallback(spec.callbackId, pageId, spec.frameId);
+        case "object":
+        case "array":
+          if (!memo)
+            memo = {specs: [], objects: []};
+
+          var idx = memo.specs.indexOf(spec);
+          if (idx != -1)
+            return memo.objects[idx];
+
+          var obj;
+          if (spec.type == "array")
+            obj = [];
+          else
+            obj = {};
+
+          memo.specs.push(spec);
+          memo.objects.push(obj);
+
+          if (spec.type == "array")
+            for (var i = 0; i < spec.items.length; i++)
+              obj.push(this.deserialize(spec.items[i], objects, pageId, memo));
+          else
+            for (var k in spec.properties)
+              obj[k] = this.deserialize(spec.properties[k], objects, pageId, memo);
+
+          return obj;
+      }
+    },
+    getObjectCache: function(page)
+    {
+      var objects = this.cache.get(page);
+      if (!objects)
+      {
+        objects = [window];
+        this.cache.set(page, objects);
+      }
+      return objects;
+    },
+    fail: function(error)
+    {
+      if (error instanceof Error)
+        error = error.message;
+      return {succeed: false, error: error};
+    },
+    handleMessage: function(message)
+    {
+      var objects = this.getObjectCache(pages[message.pageId]);
+
+      switch (message.type)
+      {
+        case "getProperty":
+          var obj = objects[message.objectId];
+
+          try
+          {
+            var value = obj[message.property];
+          }
+          catch (e)
+          {
+            return this.fail(e);
+          }
+
+          return {succeed: true, result: this.serialize(value, objects)};
+        case "setProperty":
+          var obj = objects[message.objectId];
+          var value = this.deserialize(message.value, objects, message.pageId);
+
+          try
+          {
+            obj[message.property] = value;
+          }
+          catch (e)
+          {
+            return this.fail(e);
+          }
+
+          return {succeed: true};
+        case "callFunction":
+          var func = objects[message.functionId];
+          var context = objects[message.contextId];
+
+          var args = [];
+          for (var i = 0; i < message.args.length; i++)
+            args.push(this.deserialize(message.args[i], objects, message.pageId));
+
+          try
+          {
+            var result = func.apply(context, args);
+          }
+          catch (e)
+          {
+            return this.fail(e);
+          }
+
+          return {succeed: true, result: this.serialize(result, objects)};
+        case "inspectObject":
+          var obj = objects[message.objectId];
+          var objectInfo = {properties: {}, isFunction: typeof obj == "function"};
+
+          Object.getOwnPropertyNames(obj).forEach(function(prop)
+          {
+            objectInfo.properties[prop] = {
+              enumerable: Object.prototype.propertyIsEnumerable.call(obj, prop)
+            };
+          });
+
+          if (obj.__proto__)
+            objectInfo.prototypeId = this.registerObject(obj.__proto__, objects);
+
+          if (obj == Object.prototype)
+            objectInfo.prototypeOf = "Object";
+          if (obj == Function.prototype)
+            objectInfo.prototypeOf = "Function";
+
+          return objectInfo;
+      }
+    }
+  };
+
+
+  /* Message processing */
+
+  safari.application.addEventListener("message", function(event)
+  {
+    switch (event.name)
+    {
+      case "canLoad":
+        switch (event.message.category)
+        {
+          case "loading":
+            var tab = event.target;
+            var message = event.message;
+
+            var pageId;
+            var frameId;
+
+            if (message.isTopLevel)
+            {
+              pageId = ++pageCounter;
+              frameId = 0;
+
+              if (!('_pages' in tab))
+                tab._pages = {__proto__: null};
+
+              var page = new Page(pageId, tab, message.url);
+              pages[pageId] = tab._pages[pageId] = page;
+
+              // when a new page is shown, forget the previous page associated
+              // with its tab, and reset the toolbar item if necessary.
+              // Note that it wouldn't be sufficient to do that when the old
+              // page is unloading, because Safari dispatches window.onunload
+              // only when reloading the page or following links, but not when
+              // you enter a new URL in the address bar.
+              if (!message.isPrerendered)
+                replacePage(page);
+
+              ext.pages.onLoading._dispatch(page);
+            }
             else
-              obj = {};
-
-            memo.specs.push(spec);
-            memo.objects.push(obj);
-
-            if (spec.type == "array")
-              for (var i = 0; i < spec.items.length; i++)
-                obj.push(this.deserialize(spec.items[i], objects, tab, memo));
-            else
-              for (var k in spec.properties)
-                obj[k] = this.deserialize(spec.properties[k], objects, tab, memo);
-
-            return obj;
-        }
-      },
-      createObjectCache: function(tab)
-      {
-        var objects = [window];
-
-        this.tabs.push(tab);
-        this.objects.push(objects);
-
-        tab.addEventListener("close", function()
-        {
-          var idx = this.tabs.indexOf(tab);
-
-          if (idx != -1)
-          {
-            this.tabs.splice(idx, 1);
-            this.objects.splice(idx, 1);
-          }
-        }.bind(this));
-
-        return objects;
-      },
-      getObjectCache: function(tab)
-      {
-        var idx = this.tabs.indexOf(tab);
-        var objects;
-
-        if (idx != -1)
-          objects = this.objects[idx];
-        else
-          objects = this.objects[idx] = this.createObjectCache(tab);
-
-        return objects;
-      },
-      fail: function(error)
-      {
-        if (error instanceof Error)
-          error = error.message;
-        return {succeed: false, error: error};
-      },
-      _handleMessage: function(message, tab)
-      {
-        var objects = this.getObjectCache(tab);
-
-        switch (message.type)
-        {
-          case "getProperty":
-            var obj = objects[message.objectId];
-
-            try
             {
-              var value = obj[message.property];
+              var page;
+              var parentFrame;
+
+              var lastPageId;
+              var lastPage;
+              var lastPageTopLevelFrame;
+
+              // find the parent frame and its page for this sub frame,
+              // by matching its referrer with the URL of frames previously
+              // loaded in the same tab. If there is more than one match,
+              // the most recent loaded page and frame is preferred.
+              for (var curPageId in tab._pages)
+              {
+                var curPage = pages[curPageId];
+
+                for (var i = 0; i < curPage._frames.length; i++)
+                {
+                  var curFrame = curPage._frames[i];
+
+                  if (curFrame.url == message.referrer)
+                  {
+                    pageId = curPageId;
+                    page = curPage;
+                    parentFrame = curFrame;
+                  }
+
+                  if (i == 0)
+                  {
+                    lastPageId = curPageId;
+                    lastPage = curPage;
+                    lastPageTopLevelFrame = curFrame;
+                  }
+                }
+              }
+
+              // if we can't find the parent frame and its page, fall back to
+              // the page most recently loaded in the tab and its top level frame
+              if (!page)
+              {
+                pageId = lastPageId;
+                page = lastPage;
+                parentFrame = lastPageTopLevelFrame;
+              }
+
+              frameId = page._frames.length;
+              page._frames.push({url: message.url, parent: parentFrame});
             }
-            catch (e)
-            {
-              return this.fail(e);
-            }
-
-            return {succeed: true, result: this.serialize(value, objects)};
-          case "setProperty":
-            var obj = objects[message.objectId];
-            var value = this.deserialize(message.value, objects, tab);
-
-            try
-            {
-              obj[message.property] = value;
-            }
-            catch (e)
-            {
-              return this.fail(e);
-            }
-
-            return {succeed: true};
-          case "callFunction":
-            var func = objects[message.functionId];
-            var context = objects[message.contextId];
-
-            var args = [];
-            for (var i = 0; i < message.args.length; i++)
-              args.push(this.deserialize(message.args[i], objects, tab));
-
-            try
-            {
-              var result = func.apply(context, args);
-            }
-            catch (e)
-            {
-              return this.fail(e);
-            }
-
-            return {succeed: true, result: this.serialize(result, objects)};
-          case "inspectObject":
-            var obj = objects[message.objectId];
-            var objectInfo = {properties: {}, isFunction: typeof obj == "function"};
-
-            Object.getOwnPropertyNames(obj).forEach(function(prop)
-            {
-              objectInfo.properties[prop] = {
-                enumerable: Object.prototype.propertyIsEnumerable.call(obj, prop)
-              };
-            });
-
-            if (obj.__proto__)
-              objectInfo.prototypeId = this.registerObject(obj.__proto__, objects);
-
-            if (obj == Object.prototype)
-              objectInfo.prototypeOf = "Object";
-            if (obj == Function.prototype)
-              objectInfo.prototypeOf = "Function";
-
-            return objectInfo;
-        }
-      }
-    };
-
-
-    /* Web request blocking */
-
-    ext.webRequest = {
-      onBeforeRequest: {
-        _listeners: [],
-        _urlPatterns: [],
-
-        _handleMessage: function(message, tab)
-        {
-          tab = new Tab(tab);
-
-          for (var i = 0; i < this._listeners.length; i++)
-          {
-            var regex = this._urlPatterns[i];
-
-            if ((!regex || regex.test(message.url)) && this._listeners[i](message.url, message.type, tab, 0, -1) === false)
-              return false;
-          }
-
-          return true;
-        },
-        addListener: function(listener, urls)
-        {
-          var regex;
-
-          if (urls)
-            regex = new RegExp("^(?:" + urls.map(function(url)
-            {
-              return url.split("*").map(function(s)
-              {
-                return s.replace(/([.?+^$[\]\\(){}|-])/g, "\\$1");
-              }).join(".*");
-            }).join("|") + ")($|[?#])");
-
-          this._listeners.push(listener);
-          this._urlPatterns.push(regex);
-        },
-        removeListener: function(listener)
-        {
-          var idx = this._listeners.indexOf(listener);
-
-          if (idx != -1)
-          {
-            this._listeners.splice(idx, 1);
-            this._urlPatterns.splice(idx, 1);
-          }
-        }
-      },
-      handlerBehaviorChanged: function() {}
-    };
-
-
-    /* Synchronous messaging */
-
-    safari.application.addEventListener("message", function(event)
-    {
-      if (event.name == "canLoad")
-      {
-        var handler;
-
-        switch (event.message.type)
-        {
-          case "proxy":
-            handler = proxy;
+
+            event.message = {pageId: pageId, frameId: frameId};
             break;
           case "webRequest":
-            handler = ext.webRequest.onBeforeRequest;
+            var page = pages[event.message.pageId];
+
+            event.message = ext.webRequest.onBeforeRequest._dispatch(
+              event.message.url,
+              event.message.type,
+              page,
+              page._frames[event.message.frameId]
+            );
+            break;
+          case "proxy":
+            event.message = backgroundPageProxy.handleMessage(event.message);
             break;
         }
-
-        event.message = handler._handleMessage(event.message.payload, event.target);
-      }
-    }, true);
-  }
-
-
-  /* API */
-
-  ext.windows = {
-    getAll: function(callback)
-    {
-      callback(safari.application.browserWindows.map(function(win)
-      {
-        return new Window(win);
-      }));
-    },
-    getLastFocused: function(callback)
-    {
-      callback(new Window(safari.application.activeBrowserWindow));
-    }
-  };
-
-  ext.tabs = {
-    onLoading: new LoadingTabEventTarget(safari.application),
-    onCompleted: new TabEventTarget(safari.application, "navigate", true),
-    onActivated: new TabEventTarget(safari.application, "activate", true),
-    onRemoved: new TabEventTarget(safari.application, "close", true)
-  };
-
-  ext.backgroundPage = {
-    getWindow: function()
-    {
-      return safari.extension.globalPage.contentWindow;
-    }
-  };
-
-  ext.onMessage = new MessageEventTarget(safari.application);
-
-  // TODO: Implement context menu
-  ext.contextMenus = {
-    create: function(title, contexts, onclick) {},
-    removeAll: function(callback) {}
-  };
-
-  // Safari will load the bubble once, and then show it everytime the icon is
-  // clicked. While Chrome loads it everytime you click the icon. So in order to
-  // force the same behavior in Safari, we are going to reload the page of the
-  // bubble everytime it is shown.
-  if (safari.extension.globalPage.contentWindow != window)
-    safari.application.addEventListener("popover", function()
-    {
-      document.documentElement.style.display = "none";
-      document.location.reload();
-    }, true);
+        break;
+      case "request":
+        var page = pages[event.message.pageId];
+        var sender = {page: page, frame: page._frames[event.message.frameId]};
+        page._messageProxy.handleRequest(event.message, sender);
+        break;
+      case "response":
+        pages[event.message.pageId]._messageProxy.handleResponse(event.message);
+        break;
+      case "replaced":
+        // when a prerendered page is shown, forget the previous page
+        // associated with its tab, and reset the toolbar item if necessary.
+        // Note that it wouldn't be sufficient to do that when the old
+        // page is unloading, because Safari dispatches window.onunload
+        // only when reloading the page or following links, but not when
+        // the current page is replaced with a prerendered page.
+        replacePage(pages[event.message.pageId]);
+        break;
+    }
+  });
+
+
+  /* Storage */
+
+  ext.storage = safari.extension.settings;
 })();