WordPress at a glance
action is not described

install_plugins_upload action-hook . WP 1.0

This action is documented in wp-admin/plugin-install.php

Usage

add_action( 'install_plugins_upload', 'action_function_name_5682' );
function action_function_name_5682(){
	// action...
}

Where the hook is called

In file: /wp-admin/plugin-install.php
install_plugins_upload
wp-admin/plugin-install.php 140
do_action( 'install_plugins_upload' );

Where the hook is used (in WP core)

wp-admin/includes/admin-filters.php 86
add_action( 'install_plugins_upload', 'install_plugins_upload' );