Support to repeat one song in Audio Player.

ui/file_manager/audio_player/elements/repeat_button.js

+// Copyright 2016 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.
+
+/**
+ * Repeat Button.
+ *
+ * This is for repeat button in Control Panel for Audio Player.
+ */
+Polymer({
+  is: 'repeat-button',
+
+  properties: {
+    'repeatMode': {
+      type: String,
+      notify: true,
+      reflectToAttribute: true
+    }
+  },
+
+  listeners: {
+    tap: '_tapHandler'
+  },
+
+  /**
+   * Initialize member variables.
+   */
+  created: function() {
+    /**
+     * @private {Array<string>}
+     */
+    this.modeName_ = [
+      "no-repeat",
+      "repeat-all",
+      "repeat-one"
+    ];
+  },
+
+  _tapHandler: function() {
+    this.next_();
+  },
+
+  /**
+   * Change the mode into next one.
+   * @private
+   */
+  next_: function() {
+    this.index_ = this.index_ || this.modeName_.indexOf(this.repeatMode);
+    if(this.index_ === -1)
+      return;
+
+    var nextIndex = (this.index_ + 1) % this.modeName_.length;
+    this.repeatMode = this.modeName_[nextIndex];
+    this.index_ = nextIndex;
+  },
+
+  /**
+   * Whether or not the button is active, which means it should be toggled.
+   * @param {string} mode Current mode name
+   * @return {boolean} True if the mode is repeat.
+   */
+  isActive: function(mode) {
+    return mode === "repeat-all" || mode === "repeat-one";
+  },
+});