Support to repeat one song in Audio Player.

ui/file_manager/audio_player/elements/control_panel.html

 <!--
   -- Copyright 2015 The Chromium Authors. All rights reserved.
   -- Use of this source code is governed by a BSD-style license that can be
   -- found in the LICENSE file.
   -->
 
 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/font-roboto/roboto.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-slider/paper-slider.html">
 <link rel="import" href="chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/foreground/elements/files_icon_button.html">
+<link rel="import" href="repeat_button.html">
 
 <dom-module id="control-panel">
   <link rel="import" type="css" href="control_panel.css">
   <template>
     <div class="controls">
       <div class="upper-controls audio-controls">
         <!-- Shuffle toggle button in the bottom line. -->
         <files-icon-button toggles
             id="shuffle"
             class="shuffle-mode media-button toggle"
             active="{{shuffle}}">
         </files-icon-button>
 
-        <!-- Repeat toggle button in the bottom line. -->
-        <files-icon-button toggles
-            id="repeat"
-            class="repeat media-button toggle"
-            active="{{repeat}}">
-        </files-icon-button>
+        <!-- RepeatMode toggle button in the bottom line. -->
+        <repeat-button
+            id="repeatMode"

[fukino, 2016/09/09 05:31:45]

I think we can still use id #repeat for this button. (e.g. the toggle button for
change shuffle mode has simply #shuffle.)

[harukam, 2016/09/09 11:53:45]

Acknowledged.

+            class="repeatMode media-button"

[fukino, 2016/09/09 05:31:45]

class="repeat-mode ..

[harukam, 2016/09/09 11:53:45]

Acknowledged.

+            repeat-mode="{{repeatMode}}">
+        </repeat-button>
 
         <!-- Prev button in the bottom line. -->
         <files-icon-button
             id="previous"
             class="previous media-button"
             on-click="previousClick">
         </files-icon-button>
 
         <!-- Play button in the bottom line. -->
         <files-icon-button
@@ skipping 30 matching lines @@
             class="volume media-button"
             on-click="volumeClick">
         </files-icon-button>
         <paper-slider id="volumeSlider"></paper-slider>
       </div>
     </div>
   </template>
 </dom-module>
 
 <script src="control_panel.js"></script>