[ADF-711] Drag and drop doesn't have the acceptedFilesType property (#3104)

* Added acceptedFilesType property for upload-drag-area component.
* Only those files will be uploaded which are included in acceptedFilesType.

lib/content-services/upload/components/base-upload/upload-base.ts

@@ -0,0 +1,47 @@
+/*!
+ * @license
+ * Copyright 2016 Alfresco Software, Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { FileModel } from '@alfresco/adf-core';
+import { Input } from '@angular/core';
+
+export abstract class UploadBase {
+
+    @Input()
+    acceptedFilesType: string = '*';
+
+    constructor() {}
+    /**
+     * Checks if the given file is allowed by the extension filters
+     *
+     * @param file FileModel
+     */
+    protected isFileAcceptable(file: FileModel): boolean {
+        if (this.acceptedFilesType === '*') {
+            return true;
+        }
+
+        const allowedExtensions = this.acceptedFilesType
+            .split(',')
+            .map(ext => ext.replace(/^\./, ''));
+
+        if (allowedExtensions.indexOf(file.extension) !== -1) {
+            return true;
+        }
+
+        return false;
+    }
+}