Add "Keep chrome running in background" preference.

chrome/browser/resources/options/advanced_options.js

Index: chrome/browser/resources/options/advanced_options.js
diff --git a/chrome/browser/resources/options/advanced_options.js b/chrome/browser/resources/options/advanced_options.js
index fa845a86da0b158683cc286aaf0a273fd5cb5afe..467cbaa3c5abcdce67dde22f893fb6cb243e22ed 100644
--- a/chrome/browser/resources/options/advanced_options.js
+++ b/chrome/browser/resources/options/advanced_options.js
@@ -113,6 +113,12 @@ var OptionsPage = options.OptionsPage;
         chrome.send('useTLS1CheckboxAction',
             [String($('sslUseTLS1').checked)]);
       };
+      if (!cr.isChromeOS && !cr.isMac) {

[Evan Stade, 2011/05/12 18:36:32]

can you make this a check for the existence of backgroundModeCheckbox

[Andrew T Wilson (Slow), 2011/05/12 23:34:31]

Done.

+        $('backgroundModeCheckbox').onclick = function(event) {
+          chrome.send('backgroundModeAction',
+              [String($('backgroundModeCheckbox').checked)]);
+        };
+      }
 
       // 'cloudPrintProxyEnabled' is true for Chrome branded builds on
       // certain platforms, or could be enabled by a lab.
@@ -236,6 +242,11 @@ var OptionsPage = options.OptionsPage;
     $('sslUseTLS1').disabled = disabled;
   };
 
+  // Set the checked state for the backgroundModeCheckbox element.
+  AdvancedOptions.SetBackgroundModeCheckboxState = function(checked) {
+    $('backgroundModeCheckbox').checked = checked;
+  };
+
   // Set the Cloud Print proxy UI to enabled, disabled, or processing.
   AdvancedOptions.SetupCloudPrintProxySection = function(
         disabled, label, allowed) {