Add source column to chrome://policy showing the origins of policies.

chrome/browser/resources/policy.js

Index: chrome/browser/resources/policy.js
diff --git a/chrome/browser/resources/policy.js b/chrome/browser/resources/policy.js
index bec30a7caaef25080064288f05d06cc4624f7bb7..d3836610c13af508a3edacdd8261aaf8cfe29d38 100644
--- a/chrome/browser/resources/policy.js
+++ b/chrome/browser/resources/policy.js
@@ -134,6 +134,8 @@ cr.define('policy', function() {
         this.querySelector('.level').textContent =
             loadTimeData.getString(value.level == 'recommended' ?
                 'levelRecommended' : 'levelMandatory');
+        this.querySelector('.source').textContent = value.source ?

[bartfab (slow), 2015/09/14 14:42:26]

How can |source| be not set?

[fhorschig, 2015/09/16 13:52:04]

An empty string evaluates to false. Checking for empty string now to make it
more explicit.

+            loadTimeData.getString(value.source) : '';
         this.querySelector('.value').textContent = value.value;
         this.querySelector('.expanded-value').textContent = value.value;
       }
@@ -519,7 +521,8 @@ cr.define('policy', function() {
       var newTable = window.document.createElement('table');
       var tableHead = window.document.createElement('thead');
       var tableRow = window.document.createElement('tr');
-      var tableHeadings = ['Scope', 'Level', 'Name', 'Value', 'Status'];
+      var tableHeadings = ['Scope', 'Level', 'Source', 'Name', 'Value',
+          'Status'];
       for (var i = 0; i < tableHeadings.length; i++) {
         var tableHeader = window.document.createElement('th');
         tableHeader.classList.add(tableHeadings[i].toLowerCase() + '-column');