Unify the Windows Parental Controls Platform Caching

chrome/browser/prefs/incognito_mode_prefs.h

 // Copyright (c) 2012 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_PREFS_INCOGNITO_MODE_PREFS_H_
 #define CHROME_BROWSER_PREFS_INCOGNITO_MODE_PREFS_H_
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 
 class PrefService;
 class Profile;
 
 namespace base {
 class CommandLine;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
@@ skipping 38 matching lines @@
   // Returns true if the browser should start in incognito mode.
   static bool ShouldLaunchIncognito(const base::CommandLine& command_line,
                                     const PrefService* prefs);
 
   // Returns true if |profile| can open a new Browser. This checks the incognito
   // availability policies and verifies if the |profile| type is allowed to
   // open new windows.
   static bool CanOpenBrowser(Profile* profile);
 
   // Returns whether parental controls have been enabled on the platform. This
-  // method simply returns a cached value and thus the result may be stale. May
-  // be called on any thread.
-  static bool ArePlatformParentalControlsEnabledCached();
-
-#if defined(OS_WIN)
-  // Initializes the parental control settings. Must be called on UI thread and
-  // before |ArePlatformParentalControlsEnabled|.
-  static void InitializePlatformParentalControls();
-#endif // OS_WIN
+  // method evaluates and caches if the platform controls have been enabled on
+  // the first call, which must be on the UI thread when IO and blocking are
+  // allowed. Subsequent calls may be from any thread.

[gab, 2015/03/04 19:21:20]

Also mention that this must be called on the main thread *before* other threads
are created (otherwise I think the impl is not thread-safe because a static
variable isn't -- wouldn't lead to incorrect results/corruption, but could
result in computing the value many times).

base::LazyInstance can help us work around that once we want to move the
initialization to another thread.

+  static bool ArePlatformParentalControlsEnabled() WARN_UNUSED_RESULT;
 
  private:
-  // Returns whether parental controls have been enabled on the platform, which
-  // if enabled will overrule the Availability as configured in prefs.
-  static bool ArePlatformParentalControlsEnabled();
-
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncognitoModePrefs);
 };
 
 #endif  // CHROME_BROWSER_PREFS_INCOGNITO_MODE_PREFS_H_