Media: Update total attachment count when media added or removed.

Add handlers to increment the total attachments count for the media collection when an item is added or removed.

props adamsilverstein.
Fixes #53171.
Built from https://develop.svn.wordpress.org/trunk@51191


git-svn-id: http://core.svn.wordpress.org/trunk@50800 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/media-models.js

@@ -591,6 +591,8 @@ var Attachments = Backbone.Collection.extend(/** @lends wp.media.model.Attachmen
 		this.observers.push( attachments );
 
 		attachments.on( 'add change remove', this._validateHandler, this );
+		attachments.on( 'add', this._addToTotalAttachments, this );
+		attachments.on( 'remove', this._removeFromTotalAttachments, this );
 		attachments.on( 'reset', this._validateAllHandler, this );
 		this.validateAll( attachments );
 		return this;
@@ -615,6 +617,30 @@ var Attachments = Backbone.Collection.extend(/** @lends wp.media.model.Attachmen
 
 		return this;
 	},
+	/**
+	 * Update total attachment count when items are added to a collection.
+	 *
+	 * @access private
+	 *
+	 * @since 5.8.0
+	 */
+	_removeFromTotalAttachments: function() {
+		if ( this.mirroring ) {
+			this.mirroring.totalAttachments = this.mirroring.totalAttachments - 1;
+		}
+	},
+	/**
+	 * Update total attachment count when items are added to a collection.
+	 *
+	 * @access private
+	 *
+	 * @since 5.8.0
+	 */
+	_addToTotalAttachments: function() {
+		if ( this.mirroring ) {
+			this.mirroring.totalAttachments = this.mirroring.totalAttachments + 1;
+		}
+	},
 	/**
 	 * @access private
 	 *

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-beta2-51190';
+$wp_version = '5.8-beta2-51191';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.