Always trust internal PDF viewer.

chrome/browser/resources/plugins.js

Index: chrome/browser/resources/plugins.js
diff --git a/chrome/browser/resources/plugins.js b/chrome/browser/resources/plugins.js
index 746b19231aab327806f035ffea6d371ee16e5f3e..58a3b7f42be8b08cd9be2e27fa6ea45c3bd2ed44 100644
--- a/chrome/browser/resources/plugins.js
+++ b/chrome/browser/resources/plugins.js
@@ -247,6 +247,15 @@ function isPluginEnabled(plugin) {
          plugin.enabled_mode == 'enabledByPolicy';
 }
 
+/**
+ * @param {Object} plugin An object containing the information about a plugin.
+ *     See returnPluginsData() for the format of this object.
+ * @return {boolean} Whether the plugin is fully trusted.
+ */
+function isPluginTrusted(plugin) {
+    return plugin.trusted == true;
+}
+
 // Unfortunately, we don't have notifications for plugin (list) status changes
 // (yet), so in the meanwhile just update regularly.
 setInterval(function() {