[WebUI] ClosureCompile cr.ui.DragWrapper, create a real handler class

chrome/browser/resources/extensions/drag_and_drop_handler.js

+// Copyright 2016 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.
+
+cr.define('extensions', function() {
+  'use strict';
+
+  /**
+   * @param {boolean} dragEnabled
+   * @param {!EventTarget} target
+   * @constructor
+   * @implements cr.ui.DragWrapperDelegate
+   */
+  function DragAndDropHandler(dragEnabled, target) {
+    this.dragEnabled = dragEnabled;
+    /** @private {!EventTarget} */
+    this.eventTarget_ = target;
+  }
+
+  // TODO(devlin): Un-chrome.send-ify this implementation.
+  DragAndDropHandler.prototype = {
+    /** @type {boolean} */
+    dragEnabled: false,
+
+    /** @override */
+    shouldAcceptDrag: function(e) {
+      // External Extension installation can be disabled globally, e.g. while a
+      // different overlay is already showing.
+      if (!this.dragEnabled)
+        return false;
+
+      // 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 &&
+             e.dataTransfer.types.indexOf('Files') > -1;
+    },
+
+    /** @override */
+    doDragEnter: function() {
+      chrome.send('startDrag');
+      this.eventTarget_.dispatchEvent(
+          new CustomEvent('extension-drag-started'));
+    },
+
+    /** @override */
+    doDragLeave: function() {
+      this.fireDragEnded_();
+      chrome.send('stopDrag');
+    },
+
+    /** @override */
+    doDragOver: function(e) {
+      e.preventDefault();
+    },
+
+    /** @override */
+    doDrop: function(e) {
+      this.fireDragEnded_();
+      if (e.dataTransfer.files.length != 1)
+        return;
+
+      var toSend = '';
+      // Files lack a check if they're a directory, but we can find out through
+      // its item entry.
+      for (var i = 0; i < e.dataTransfer.items.length; ++i) {
+        if (e.dataTransfer.items[i].kind == 'file' &&
+            e.dataTransfer.items[i].webkitGetAsEntry().isDirectory) {
+          toSend = 'installDroppedDirectory';
+          break;
+        }
+      }
+      // Only process files that look like extensions. Other files should
+      // navigate the browser normally.
+      if (!toSend &&
+          /\.(crx|user\.js|zip)$/i.test(e.dataTransfer.files[0].name)) {
+        toSend = 'installDroppedFile';
+      }
+
+      if (toSend) {
+        e.preventDefault();
+        chrome.send(toSend);
+      }
+    },
+
+     /** @private */
+    fireDragEnded_: function() {
+      this.eventTarget_.dispatchEvent(new CustomEvent('extension-drag-ended'));
+    }
+  };
+
+  return {
+    DragAndDropHandler: DragAndDropHandler,
+  };
+});