[add] support battery.vim

autoload/airline/extensions.vim

@@ -450,6 +450,11 @@ function! airline#extensions#load()
     call add(s:loaded_ext, 'searchcount')
   endif
 
+  if get(g:, 'loaded_battery', 0) && get(g:, 'airline#extensions#battery#enabled', 0)
+    call airline#extensions#battery#init(s:ext)
+    call add(s:loaded_ext, 'battery')
+  endif
+
   if !get(g:, 'airline#extensions#disable_rtp_load', 0)
     " load all other extensions, which are not part of the default distribution.
     " (autoload/airline/extensions/*.vim outside of our s:script_path).

autoload/airline/extensions/battery.vim

@@ -0,0 +1,20 @@
+" MIT License. Copyright (c) 2014-2020 Mathias Andersson et al.
+" Plugin: https://github.com/lambdalisue/battery.vim
+" vim: et ts=2 sts=2 sw=2
+
+scriptencoding utf-8
+
+if !exists('g:loaded_battery')
+  finish
+endif
+
+function! airline#extensions#battery#status(...) abort
+  if !exists('g:battery#update_statusline') 
+    let g:battery#update_statusline = 1
+  endif
+  let w:airline_section_z = '%{battery#component()}'
+endfunction
+
+function! airline#extensions#battery#init(ext) abort
+  call a:ext.add_statusline_func('airline#extensions#battery#status')
+endfunction