function ccom_page_alter(&$page) {
  if (array_key_exists('#account',$page['content']['system_main'])) {
    $account = $page['content']['system_main']['#account'];

    if (isset($account)) {
      drupal_set_title($account->field_complete_name['und'][0]['safe_value']);
    }
  }
}

function ccom_preprocess_user_profile(&$variables) {
  drupal_set_title($variables['elements']['#account']->field_complete_name[LANGUAGE_NONE][0]['safe_value']);
}

function ccom_preprocess(&$variables, $hook) {
  dpm($hook);
}

function ccom_preprocess_user_profile(&$variables) {
  dpm($variables);
  drupal_set_title('mytitle');
}

function ccom_preprocess_page(&$variables) {
  dpm($variables);
  drupal_set_title('mytitle');
}

function YOUR_MODULE_menu_alter(&$items) {
    // Change the title of user profile pages to the user's name.  Gak.
    $items['user/%user']['title callback'] = 'YOUR_MODULE_user_page_title';
}

function YOUR_MODULE_user_page_title() {
    if (arg(0) == 'user') {
        // Load uid from url
        $user = user_load(arg(1));
        // Get the full user name somehow; here, I'm calling a function of my own.
        $output = get_user_full_name($user);
    }
    // Fallback to username if no fields are present
    if (empty($output)) {
        $output = $user->name;
    }
    return $output;
}

function hook_username_alter(&$name, $account) {
  if (arg(0) == 'user' && is_numeric(arg(1))) {
    if (isset($account->uid)) {
      $name = $account->your_field_name['und'][0]['safe_value'];
    }
  }
}

function mymodule_user_view($account, $view_mode, $langcode) {
  if ($account->uid == 1 && $view_mode == 'full') {
     drupal_set_title('my custom title');
  }
}