Make the repeat button accessible by keyboard.

ui/file_manager/audio_player/elements/repeat_button.html

Index: ui/file_manager/audio_player/elements/repeat_button.html
diff --git a/ui/file_manager/audio_player/elements/repeat_button.html b/ui/file_manager/audio_player/elements/repeat_button.html
index c38390cafdf18e56b2bf049a21b1577c1e1c4a4a..e3cd14057862e2df83543ca0dc7910f3e0715397 100644
--- a/ui/file_manager/audio_player/elements/repeat_button.html
+++ b/ui/file_manager/audio_player/elements/repeat_button.html
@@ -4,12 +4,14 @@
   -->
 
 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
-<link rel="import" href="chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/foreground/elements/files_toggle_ripple.html">
+<link rel="import" href="chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/foreground/elements/files_icon_button.html">
 
 <dom-module id="repeat-button">
   <link rel="import" type="css" href="repeat_button.css">
   <template>
-    <files-toggle-ripple activated="[[isActive(repeatMode)]]" class$="{{repeatMode}}"></files-toggle-ripple>
+    <!-- TODO(yamaguchi): Eliminate extra ripple effect upon mouse click. -->

[fukino, 2016/11/10 07:09:35]

I'm sorry for jumping in this already-agreed approach!

If you don't have a plan to fix this regression at this moment, I think it is
better to stick with the previous implementation by copying necessary
logic/style from files-icon-button.
You can factor out the common parts to shared style and behavior later.

[yamaguchi, 2016/11/10 08:14:53]

Resolved the TODO now.
I'm sorry, this was very simple to fix.

+    <files-icon-button active="[[isActive(repeatMode)]]"
+                       repeat-mode$="{{repeatMode}}"></files-icon-button>
   </template>
 
   <script src="repeat_button.js"></script>