Adding button in list view

recordlist.js

({
	extendsFrom:'RecordlistView',
	initialize:function(options){
		this._super('initialize',[options]);
		this.context.on('list:updatecurrentsize:fire',this.mass_update_currentsize,this);
	},
	/**
	 * Function to mass update the current size
	 * for all selected accounts
	 * Written by: Ajay Kumar
	 * Dated: 7th Dec 2015
	 */
	mass_update_currentsize:function(){
		//loading label
		app.alert.show('updating-inprogress', {level: 'process', title: app.lang.get('LBL_PRO_ENABLE')});
		var self=this;
		var massCollection = this.context.get("mass_collection");
		var id_array = [];
		massCollection.each(function(data){	
			id_array.push(data.id);
		});
		//call api to update current size of selected mandates
		app.api.call('create', app.api.buildURL('Accounts/updateCurrentSize'),{man_id_array:id_array},{
			success: function(data){
				//dismiss progress label
				app.alert.dismiss('updating-inprogress');
				//if successful
				if(data.status) {
					app.alert.show('update-success', {
						level: 'success',
						messages: app.lang.get('TPL_MASSUPDATE_SUCCESS', self.module, { num: data.records }),
						autoClose: true,
						autoCloseDelay: 5000
					});
				//if error
				} else {
					app.alert.show('update-failure', {
						level: 'error',
						messages: app.lang.get('ERR_MOBILE_FILE_READ'),
						autoClose: true,
						autoCloseDelay: 5000
					});
				}
				//refresh the list
				app.router.refresh();
			},
		});			
	}
})

recordlist.php

<?php

if(!defined('sugarEntry'))define('sugarEntry',true);

$viewdefs['Accounts']['base']['view']['recordlist'] = array(
    'favorite' => true,
    'following' => true,
    'sticky_resizable_columns' => true,
    'selection' => array(
        'type' => 'multi',
        'actions' => array(
            array(
                'name' => 'edit_button',
                'type' => 'button',
                'label' => 'LBL_MASS_UPDATE',
                'primary' => true,
                'events' => array(
                    'click' => 'list:massupdate:fire',
                ),
                'acl_action' => 'massupdate',
            ),
            array(
                'name' => 'calc_field_button',
                'type' => 'button',
                'label' => 'LBL_UPDATE_CALC_FIELDS',
                'events' => array(
                    'click' => 'list:updatecalcfields:fire',
                ),
                'acl_action' => 'massupdate',
            ),
            array(
                'name' => 'merge_button',
                'type' => 'button',
                'label' => 'LBL_MERGE',
                'primary' => true,
                'events' => array(
                    'click' => 'list:mergeduplicates:fire',
                ),
                'acl_action' => 'edit',
            ),
            array(
                'name' => 'delete_button',
                'type' => 'button',
                'label' => 'LBL_DELETE',
                'acl_action' => 'delete',
                'primary' => true,
                'events' => array(
                    'click' => 'list:massdelete:fire',
                ),
            ),
            array(
                'name' => 'export_button',
                'type' => 'button',
                'label' => 'LBL_EXPORT',
                'acl_action' => 'export',
                'primary' => true,
                'events' => array(
                    'click' => 'list:massexport:fire',
                ),
            ),
            array(
				'name' => 'update_currentsize_button',
				'type' => 'button',
				'label' => 'LBL_UPDATE_CURRENT_SIZE',
				 'events' => array(
					'click' => 'list:updatecurrentsize:fire',
				),
				'acl_action' => 'export',
			),
        ),
    ),
    'rowactions' => array(
        'actions' => array(
            array(
                'type' => 'rowaction',
                'css_class' => 'btn',
                'tooltip' => 'LBL_PREVIEW',
                'event' => 'list:preview:fire',
                'icon' => 'fa-eye',
                'acl_action' => 'view',
            ),
            array(
                'type' => 'rowaction',
                'name' => 'edit_button',
                'label' => 'LBL_EDIT_BUTTON',
                'event' => 'list:editrow:fire',
                'acl_action' => 'edit',
            ),
            array(
                'type' => 'follow',
                'name' => 'follow_button',
                'event' => 'list:follow:fire',
                'acl_action' => 'view',
            ),
            array(
                'type' => 'rowaction',
                'name' => 'delete_button',
                'event' => 'list:deleterow:fire',
                'label' => 'LBL_DELETE_BUTTON',
                'acl_action' => 'delete',
            ),
        ),
    ),
    'last_state' => array(
        'id' => 'record-list',
    ),
);