Update on Issue 8118003.

chrome/browser/resources/options/font_settings.js

Index: chrome/browser/resources/options/font_settings.js
diff --git a/chrome/browser/resources/options/font_settings.js b/chrome/browser/resources/options/font_settings.js
index dfde2f60e22c21b39e4e79c2b236e49f0f880863..35372db12f0b4d3f443cb01bcad1ffa3c175906b 100644
--- a/chrome/browser/resources/options/font_settings.js
+++ b/chrome/browser/resources/options/font_settings.js
@@ -6,6 +6,8 @@ cr.define('options', function() {
 
   var OptionsPage = options.OptionsPage;
 
+  const SizeDifferenceFixedStandard = 3;

[Peter Kasting, 2011/11/04 16:22:33]

Nit: I suggest adding some comments on what this means, why it's here, etc.

[groby-ooo-7-16, 2011/11/08 19:05:17]

nit: Please uppercase simple primitive constants. 

[rosen.dash, 2011/11/09 07:04:02]

Done.

[rosen.dash, 2011/11/09 07:04:02]

Done.

+
   /**
    * FontSettings class
    * Encapsulated handling of the 'Fonts and Encoding' page.
@@ -34,6 +36,8 @@ cr.define('options', function() {
           22, 24, 26, 28, 30, 32, 34, 36, 40, 44, 48, 56, 64, 72];
       standardFontRange.continuous = false;
       standardFontRange.notifyChange = this.standardRangeChanged_.bind(this);
+      standardFontRange.notifyPrefChange =
+          this.standardFontSizeChanged_.bind(this);
 
       var minimumFontRange = $('minimum-font-size');
       minimumFontRange.valueMap = [6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
@@ -86,6 +90,22 @@ cr.define('options', function() {
       fontSampleEl = $('sans-serif-font-sample');
       this.setUpFontSample_(fontSampleEl, value, fontSampleEl.style.fontFamily,
                             true);
+
+      fontSampleEl = $('fixed-font-sample');
+      this.setUpFontSample_(fontSampleEl, value - SizeDifferenceFixedStandard,

[Peter Kasting, 2011/11/04 16:22:33]

Nit: Should someone somewhere assert that this will never go negative?

[groby-ooo-7-16, 2011/11/08 19:05:17]

Technically, standardRange has a minimum of '9', so this should never happen.

If you add assert, please add to initializePage instead, assuring that
standardFontRange.valueMap[0] < SizeDifferenceFixedStandard

Here's a reference implementation for assert:
http://codesearch.google.com/codesearch/p#OAMlx_jo-ck/src/chrome/browser/reso...

On 2011/11/04 16:22:33, Peter Kasting wrote:

[rosen.dash, 2011/11/09 07:04:02]

I think that it's not necessary to add an assert. So I am skipping it.

+                            fontSampleEl.style.fontFamily, false);
+    },
+
+    /**
+     * Sets the 'default_fixed_font_size' preference when the standard font
+     * size has been changed by the user.
+     * @param {Element} el The slider input element.
+     * @param {number} value The mapped value that has been saved.
+     * @private
+     */
+    standardFontSizeChanged_: function(el, value) {
+      Preferences.setIntegerPref('webkit.webprefs.default_fixed_font_size',
+                                 value - SizeDifferenceFixedStandard, '');
     },
 
     /**