Always trust internal PDF viewer.

chrome/browser/ui/webui/plugins/plugins.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 struct MimeType {
   string description;
   array<string> file_extensions;
   string mime_type;
 };
 
 struct PluginFile {
   string description;
   string enabled_mode;
   array<MimeType> mime_types;
   string name;
   string path;
   string type;
   string version;
 };
 
 struct PluginData {
   bool always_allowed;
+  bool trusted;
   string description;
   bool critical;
   string enabled_mode;
   string id;
   string name;
   string update_url;
   string version;
   array<PluginFile> plugin_files;
 };
 
 interface PluginsHandlerMojo {
   GetPluginsData() => (array<PluginData> plugins);
   GetShowDetails() => (bool show_details);
   SaveShowDetailsToPrefs(bool details_mode);
   SetPluginAlwaysAllowed(string plugin, bool allowed);
   SetPluginEnabled(string plugin_path, bool enable);
   SetPluginGroupEnabled(string group_name, bool enable);
   SetClientPage(PluginsPageMojo page);
 };
 
 interface PluginsPageMojo {
   OnPluginsUpdated(array<PluginData> plugins);
 };