Add a bulk edit mode.

Add an option to wp.media.view.AttachmentsBrowser `bulkEdit`,
which defaults to false. When set to true, conditionally create
a SelectionBulkEdit view when multiple items are selected.

Multiple delete now possible.

core-js-overrides/media-views.js

@@ -2145,6 +2145,7 @@
 				filters:    state.get('filterable'),
 				display:    state.get('displaySettings'),
 				dragInfo:   state.get('dragInfo'),
+				bulkEdit:   true,
 
 				suggestedWidth:  state.get('suggestedWidth'),
 				suggestedHeight: state.get('suggestedHeight'),
@@ -5521,6 +5522,7 @@
 				filters: false,
 				search:  true,
 				display: false,
+				bulkEdit: false,
 
 				AttachmentView: media.view.Attachment.Library
 			});
@@ -5675,17 +5677,42 @@
 			}
 
 			selection.on( 'selection:single', this.createSingle, this );
+			if ( this.options.bulkEdit ) {
+				selection.on( 'selection:single', this.maybeCreateMultiple, this );
+			}
 			selection.on( 'selection:unsingle', this.disposeSingle, this );
 
 			if ( selection.single() ) {
 				this.createSingle();
 			}
 		},
 
+		maybeCreateMultiple: function() {
+			var sidebar = this.sidebar,
+				single = this.options.selection.single();
+
+			// Bail early if there isn't a multi-selection.
+			if ( this.options.selection.length <=1 ) {
+				sidebar.unset( 'selection' );
+				return;
+			}
+			sidebar.set( 'selection', new media.view.SelectionBulkEdit({
+				controller: this.controller,
+				collection: this.options.selection,
+				priority:   -40
+			}).render() );
+		},
+
 		createSingle: function() {
 			var sidebar = this.sidebar,
 				single = this.options.selection.single();
 
+			// If bulk edit is enabled and more than one attachment has been
+			// selected, bail early.
+			if ( this.options.bulkEdit && this.options.selection.length > 1 ) {
+				return;
+			}
+
 			sidebar.set( 'details', new media.view.Attachment.Details({
 				controller: this.controller,
 				model:      single,
@@ -5793,6 +5820,31 @@
 		}
 	});
 
+	/**
+	 * wp.media.view.SelectionBulkEdit
+	 *
+	 * @constructor
+	 * @augments wp.media.view.Selection
+	 * @augments wp.media.View
+	 * @augments wp.Backbone.View
+	 * @augments Backbone.View
+	 */
+	media.view.SelectionBulkEdit = media.view.Selection.extend({
+		template:  media.template('media-selection-bulk-edit'),
+		events: {
+			'click .clear-selection': 'clear',
+			'click .delete-selection':  'delete'
+		},
+
+		// Delete click handler.
+		delete: function( event ) {
+			event.preventDefault();
+			// Fold this string into the l10n object later.
+			if ( confirm( "You are about to permanently delete these items.\n'Cancel' to stop, 'OK' to delete." ) ) {
+				this.collection.invoke( 'destroy' );
+			}
+		}
+	});
 
 	/**
 	 * wp.media.view.Attachment.Selection

media-template.php

@@ -0,0 +1,10 @@
+<script type="text/html" id="tmpl-media-selection-bulk-edit">
+	<div class="selection-info">
+		<span class="count"></span>
+		<# if ( data.clearable ) { #>
+			<a class="clear-selection" href="#"><?php _e('Clear'); ?></a>
+		<# } #>
+		<a class="delete-selection" href="#"><?php _e('Delete'); ?></a>
+	</div>
+	<div class="selection-view"></div>
+</script>

styles.css

@@ -41,4 +41,18 @@
 	background: rgba(0,0,0,0.6);
 	color: #fff;
 	cursor: default;
+}
+
+#media-library .media-selection {
+	position: static;
+}
+#media-library .attachments-browser .media-selection {
+	height: auto;
+}
+#media-library .attachments-browser .media-selection .selection-view {
+	display: block;
+}
+#media-library .attachments-browser .media-selection .attachments {
+	position: static;
+	height: auto;
 }

wp-media-grid.php

@@ -17,6 +17,8 @@ function __construct() {
 
 		add_action( 'load-upload.php', array( $this, 'media_grid' ) );
 		add_action( 'admin_init', array( $this, 'enqueue' ) );
+		add_action( 'wp_enqueue_media', array( $this, 'wp_enqueue_media' ) );
+
 	}
 
 
@@ -84,6 +86,10 @@ public function enqueue() {
 		wp_enqueue_style( 'wp-media-grid', plugins_url( 'styles.css', __FILE__ ) );
 		wp_enqueue_script( 'live-filter', plugins_url( 'libs/jquery.liveFilter.js', __FILE__ ) );
 	}
+
+	public function wp_enqueue_media() {
+		require_once( plugin_dir_path( __FILE__ ) . 'media-template.php' );
+	}
 }
 
 /**