Allow whitelisted prefs to be displayed in ChromeOS in chrome://local-state.

chrome/browser/ui/webui/local_state/local_state_ui.h

 // Copyright 2014 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_LOCAL_STATE_LOCAL_STATE_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_LOCAL_STATE_LOCAL_STATE_UI_H_
 
+#include <string>
+#include <vector>
+
 #include "base/macros.h"
 #include "content/public/browser/web_ui_controller.h"
 
+namespace base {
+class DictionaryValue;
+}
+
+// Namespace for exposing the method for unit tests.
+namespace internal {
+
+// Removes elements from |prefs| where the key does not match any of the
+// prefixes in |valid_prefixes|.
+void FilterPrefs(const std::vector<std::string>& valid_prefixes,
+                 base::DictionaryValue* prefs);
+
+}  // namespace internal
+
 // Controller for chrome://local-state/ page.
 class LocalStateUI : public content::WebUIController {
  public:
   explicit LocalStateUI(content::WebUI* web_ui);
   ~LocalStateUI() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LocalStateUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_LOCAL_STATE_LOCAL_STATE_UI_H_