Add a first-class off-store install UI to chrome://extensions/.

chrome/browser/resources/extensions/extensions.js

 // Copyright (c) 2012 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.
 
+<include src="../shared/js/cr/ui/drag_wrapper.js"></include>
 <include src="../uber/uber_utils.js"></include>
 <include src="extension_list.js"></include>
 <include src="pack_extension_overlay.js"></include>
 
 // Used for observing function of the backend datasource for this page by
 // tests.
 var webui_responded_ = false;
 
 cr.define('extensions', function() {
   var ExtensionsList = options.ExtensionsList;
 
+  // Implements the DragWrapper handler interface.
+  var dragWrapperHandler = {
+    shouldAcceptDrag: function(e) {

[Evan Stade, 2012/05/04 19:57:17]

the js style checker will probably complain if you don't at least @inheritdoc

+      // We can't access filenames during the 'dragenter' event, so we have to
+      // wait until 'drop' to decide whether to do something with the file or
+      // not.
+      // See: http://www.w3.org/TR/2011/WD-html5-20110113/dnd.html#concept-dnd-p
+      return e.dataTransfer.types.indexOf('Files') > -1;
+    },
+    doDragEnter: function() {
+      chrome.send('startDrag');
+      ExtensionSettings.showOverlay(null);
+      ExtensionSettings.showOverlay($('dropTargetOverlay'));
+    },
+    doDragLeave: function() {
+      ExtensionSettings.showOverlay(null);
+      chrome.send('stopDrag');
+    },
+    doDragOver: function(e) {
+    },
+    doDrop: function(e) {
+      // Only process files that look like extensions. Other files should
+      // navigate the browser normally.
+      if (!e.dataTransfer.files.length ||
+          !/\.crx$/.test(e.dataTransfer.files[0].name)) {
+        return;
+      }
+
+      chrome.send('installDroppedFile');
+      ExtensionSettings.showOverlay(null);
+      e.preventDefault();
+    }
+  };
+
   /**
    * ExtensionSettings class
    * @class
    */
   function ExtensionSettings() {}
 
   cr.addSingletonGetter(ExtensionSettings);
 
   ExtensionSettings.prototype = {
     __proto__: HTMLDivElement.prototype,
@@ skipping 20 matching lines @@
           this.handleDevControlsTransitionEnd_.bind(this));
 
       // Set up the three dev mode buttons (load unpacked, pack and update).
       $('load-unpacked').addEventListener('click',
           this.handleLoadUnpackedExtension_.bind(this));
       $('pack-extension').addEventListener('click',
           this.handlePackExtension_.bind(this));
       $('update-extensions-now').addEventListener('click',
           this.handleUpdateExtensionNow_.bind(this));
 
+      if (!loadTimeData.getBoolean('offStoreInstallEnabled')) {
+        this.dragWrapper_ =
+            new cr.ui.DragWrapper(document.body, dragWrapperHandler);
+      }
+
       var packExtensionOverlay = extensions.PackExtensionOverlay.getInstance();
       packExtensionOverlay.initializePage();
+
+      cr.ui.overlay.setupOverlay($('dropTargetOverlay'));
     },
 
     /**
      * Handles the Load Unpacked Extension button.
      * @param {Event} e Change event.
      * @private
      */
     handleLoadUnpackedExtension_: function(e) {
       chrome.send('extensionSettingsLoadUnpackedExtension');
 
@@ skipping 174 matching lines @@
   return {
     ExtensionSettings: ExtensionSettings
   };
 });
 
 var ExtensionSettings = extensions.ExtensionSettings;
 
 window.addEventListener('load', function(e) {
   ExtensionSettings.getInstance().initialize();
 });