Updated background color for extensions page using MD default styles.

chrome/browser/resources/md_extensions/extensions.html

Index: chrome/browser/resources/md_extensions/extensions.html
diff --git a/chrome/browser/resources/md_extensions/extensions.html b/chrome/browser/resources/md_extensions/extensions.html
index bd13713892315485504db1d9750d855f2914525b..531a160533b1f22afb98321fd3d8a7a34151c722 100644
--- a/chrome/browser/resources/md_extensions/extensions.html
+++ b/chrome/browser/resources/md_extensions/extensions.html
@@ -5,10 +5,12 @@
   <title>$i18n{title}</title>
   <link rel="import" href="chrome://resources/html/polymer.html">
   <link rel="import" href="chrome://extensions/manager.html">
+  <link rel="stylesheet" href="chrome://resources/css/md_colors.css">
   <style>
     html {
-      background: #e6e6e6;
+      background: var(--md-background-color);
     }
+
     html,
     body {
       font-family: Roboto;