Refactor extension bindings to share code, avoid exposing hidden variables

chrome/renderer/resources/event_bindings.js

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // -----------------------------------------------------------------------------
 // NOTE: If you change this file you need to touch renderer_resources.grd to
 // have your change take effect.
 // -----------------------------------------------------------------------------
 
 var chrome = chrome || {};
 (function () {
+  native function GetChromeHidden();
   native function AttachEvent(eventName);
   native function DetachEvent(eventName);
+  native function GetNextRequestId();
+
+  var chromeHidden = GetChromeHidden();
 
   // Event object.  If opt_eventName is provided, this object represents
   // the unique instance of that named event, and dispatching an event
   // with that name will route through this object's listeners.
   //
   // Example:
   //   chrome.tabs.onChanged = new chrome.Event("tab-changed");
   //   chrome.tabs.onChanged.addListener(function(data) { alert(data); });
-  //   chrome.Event.dispatch_("tab-changed", "hi");
+  //   chromeHidden.Event.dispatch("tab-changed", "hi");
   // will result in an alert dialog that says 'hi'.
   chrome.Event = function(opt_eventName) {
     this.eventName_ = opt_eventName;
     this.listeners_ = [];
   };
 
   // A map of event names to the event object that is registered to that name.
-  chrome.Event.attached_ = {};
+  var attachedNamedEvents = {};
+
+  // An array of all attached event objects, used for detaching on unload.
+  var allAttachedEvents = [];
+
+  chromeHidden.Event = {};
 
   // Dispatches a named event with the given JSON array, which is deserialized
   // before dispatch. The JSON array is the list of arguments that will be
   // sent with the event callback.
-  chrome.Event.dispatchJSON_ = function(name, args) {
-    if (chrome.Event.attached_[name]) {
+  chromeHidden.Event.dispatchJSON = function(name, args) {
+    if (attachedNamedEvents[name]) {
       if (args) {
         args = JSON.parse(args);
       }
-      chrome.Event.attached_[name].dispatch.apply(
-          chrome.Event.attached_[name], args);
+      attachedNamedEvents[name].dispatch.apply(
+          attachedNamedEvents[name], args);
     }
   };
 
   // Dispatches a named event with the given arguments, supplied as an array.
-  chrome.Event.dispatch_ = function(name, args) {
-    if (chrome.Event.attached_[name]) {
-      chrome.Event.attached_[name].dispatch.apply(
-          chrome.Event.attached_[name], args);
+  chromeHidden.Event.dispatch = function(name, args) {
+    if (attachedNamedEvents[name]) {
+      attachedNamedEvents[name].dispatch.apply(
+          attachedNamedEvents[name], args);
     }
   };
 
   // Registers a callback to be called when this event is dispatched.
   chrome.Event.prototype.addListener = function(cb) {
     this.listeners_.push(cb);
     if (this.listeners_.length == 1) {
       this.attach_();
     }
   };
@@ skipping 38 matching lines @@
       } catch (e) {
         console.error(e);
       }
     }
   };
 
   // Attaches this event object to its name.  Only one object can have a given
   // name.
   chrome.Event.prototype.attach_ = function() {
     AttachEvent(this.eventName_);
-    this.unloadHandler_ = this.detach_.bind(this);
-    window.addEventListener('unload', this.unloadHandler_, false);
+    allAttachedEvents[allAttachedEvents.length] = this;
     if (!this.eventName_)
       return;
 
-    if (chrome.Event.attached_[this.eventName_]) {
+    if (attachedNamedEvents[this.eventName_]) {
       throw new Error("chrome.Event '" + this.eventName_ +
                       "' is already attached.");
     }
 
-    chrome.Event.attached_[this.eventName_] = this;
+    attachedNamedEvents[this.eventName_] = this;
   };
 
   // Detaches this event object from its name.
   chrome.Event.prototype.detach_ = function() {
-    window.removeEventListener('unload', this.unloadHandler_, false);
+    var i = allAttachedEvents.indexOf(this);
+    if (i >= 0)
+      delete allAttachedEvents[i];
     DetachEvent(this.eventName_);
     if (!this.eventName_)
       return;
 
-    if (!chrome.Event.attached_[this.eventName_]) {
+    if (!attachedNamedEvents[this.eventName_]) {
       throw new Error("chrome.Event '" + this.eventName_ +
                       "' is not attached.");
     }
 
-    delete chrome.Event.attached_[this.eventName_];
+    delete attachedNamedEvents[this.eventName_];
   };
+
+  // Callback handling.
+  var callbacks = [];
+  chromeHidden.handleResponse = function(requestId, name,
+                                         success, response, error) {
+    try {
+      if (!success) {
+        if (!error)
+          error = "Unknown error."
+        console.error("Error during " + name + ": " + error);
+        return;
+      }
+
+      if (callbacks[requestId]) {
+        if (response) {
+          callbacks[requestId](JSON.parse(response));
+        } else {
+          callbacks[requestId]();
+        }
+      }
+    } finally {
+      delete callbacks[requestId];
+    }
+  };
+
+  // Send an API request and optionally register a callback.
+  chromeHidden.sendRequest = function(request, args, callback) {
+    // JSON.stringify doesn't support a root object which is undefined.
+    if (args === undefined)
+      args = null;
+    var sargs = JSON.stringify(args);
+    var requestId = GetNextRequestId();
+    var hasCallback = false;
+    if (callback) {
+      hasCallback = true;
+      callbacks[requestId] = callback;
+    }
+    request(sargs, requestId, hasCallback);
+  }
+
+  // Special unload event: we don't use the DOM unload because that slows
+  // down tab shutdown.  On the other hand, this might not always fire, since
+  // Chrome will terminate renderers on shutdown (SuddenTermination).
+  chromeHidden.onUnload = new chrome.Event();
+
+  chromeHidden.dispatchOnUnload = function() {
+    chromeHidden.onUnload.dispatch();
+    for (var i in allAttachedEvents)
+      allAttachedEvents[i].detach_();
+  }
 })();