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 "base/values.h"

[Alexei Svitkine (slow), 2016/04/25 21:30:13]

Nit: You can forward declare base::DictionaryValue instead.

[hamelphi, 2016/04/26 15:25:28]

Done.

However, can you explain why this is better in this case? In the Google Style
Guide, forward declarations are frowned upon, since it can potentially cause
more trouble down the road (go/fwd_decl_harmful). 

[Alexei Svitkine (slow), 2016/04/26 15:33:34]

Chromium diverges from Google Style here - as the build time improvements are
more relevant for Chromium since most builds are done locally.

See:
https://www.chromium.org/developers/coding-style#TOC-Forward-declarations-vs....

 #include "content/public/browser/web_ui_controller.h"
 
+namespace internal {

[Alexei Svitkine (slow), 2016/04/25 21:30:13]

Nit: Add a short comment about the purpose of this namespace (i.e. for testing).

[hamelphi, 2016/04/26 15:25:28]

Done.

+void FilterPrefs(const std::vector<std::string>& valid_prefixes,

[Alexei Svitkine (slow), 2016/04/25 21:30:13]

Nit: Add a short comment about what this function does.

[hamelphi, 2016/04/26 15:25:28]

Done.

+                 base::DictionaryValue* prefs);
+}
+
 // 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_