MD Settings: [further] robustify default zoom level handling

chrome/browser/resources/settings/appearance_page/appearance_page.js

Index: chrome/browser/resources/settings/appearance_page/appearance_page.js
diff --git a/chrome/browser/resources/settings/appearance_page/appearance_page.js b/chrome/browser/resources/settings/appearance_page/appearance_page.js
index 49f9fc1a5fdec41fe40e61283174fa23907823fa..cb443e15c4fd4da5950c63608b84ed8db7ae16c0 100644
--- a/chrome/browser/resources/settings/appearance_page/appearance_page.js
+++ b/chrome/browser/resources/settings/appearance_page/appearance_page.js
@@ -112,7 +112,15 @@ Polymer({
     // TODO(dschuyler): Look into adding a listener for the
     // default zoom percent.
     chrome.settingsPrivate.getDefaultZoom(function(zoom) {
-      this.$.zoomLevel.value = zoom;
+      assert(this.pageZoomLevels_.length == this.$.zoomLevel.options.length);
+      for (var i = 0; i < this.pageZoomLevels_.length; ++i) {

[dpapad, 2016/11/10 00:30:58]

If we have to iterate over zoom levels, would it make sense to add a binding
instead?

 <option value="[[item]]"
selected$="[[isSelected_(item,zoomLevel)]]">[[formatZoom_(item)]]%</option>

properties: {
 ...
 zoomLevel: Number
}

isSelected_: function(item) {
  return Math.abs(item - this.zoomLevel) <= 0.001;
}

[Dan Beam, 2016/11/10 01:22:11]

Done.

+        // See content::ZoomValuesEqual().
+        if (Math.abs(this.pageZoomLevels_[i] - zoom) <= 0.001) {
+          this.$.zoomLevel.selectedIndex = i;
+          return;
+        }
+      }
+      assertNotReached();
     }.bind(this));
   },