Rolling forward https://codereview.chromium.org/1155683008/ which was

third_party/polymer/v0_8/components-chromium/paper-progress/paper-progress-extracted.js

-
-  Polymer({
-
-    is: 'paper-progress',
-
-    behaviors: [
-      Polymer.IronRangeBehavior
-    ],
-
-    properties: {
-
-      /**
-       * The number that represents the current secondary progress.
-       */
-      secondaryProgress: {
-        type: Number,
-        value: 0,
-        notify: true
-      },
-
-      /**
-       * The secondary ratio
-       */
-      secondaryRatio: {
-        type: Number,
-        value: 0,
-        readOnly: true,
-        observer: '_secondaryRatioChanged'
-      },
-
-      /**
-       * Use an indeterminate progress indicator.
-       */
-      indeterminate: {
-        type: Boolean,
-        value: false,
-        notify: true,
-        observer: '_toggleIndeterminate'
-      }
-    },
-
-    observers: [
-      '_ratioChanged(ratio)',
-      '_secondaryProgressChanged(secondaryProgress, min, max)'
-    ],
-
-    _toggleIndeterminate: function() {
-      // If we use attribute/class binding, the animation sometimes doesn't translate properly
-      // on Safari 7.1. So instead, we toggle the class here in the update method.
-      this.toggleClass('indeterminate', this.indeterminate, this.$.activeProgress);
-    },
-
-    _transformProgress: function(progress, ratio) {
-      var transform = 'scaleX(' + (ratio / 100) + ')';
-      progress.style.transform = progress.style.webkitTransform = transform;
-    },
-
-    _ratioChanged: function(ratio) {
-      this._transformProgress(this.$.activeProgress, ratio);
-    },
-
-    _secondaryRatioChanged: function(secondaryRatio) {
-      this._transformProgress(this.$.secondaryProgress, secondaryRatio);
-    },
-
-    _secondaryProgressChanged: function() {
-      this.secondaryProgress = this._clampValue(this.secondaryProgress);
-      this._setSecondaryRatio(this._calcRatio(this.secondaryProgress) * 100);
-    }
-
-  });
-