Cache the Windows Parental Controls Platform Answer

chrome/browser/prefs/incognito_mode_prefs.cc

Index: chrome/browser/prefs/incognito_mode_prefs.cc
diff --git a/chrome/browser/prefs/incognito_mode_prefs.cc b/chrome/browser/prefs/incognito_mode_prefs.cc
index e0255d4947d11a90c3d2e5fbbd56f707459c811b..8d756e8e5c1a979f8c09cf544f1aac271833451f 100644
--- a/chrome/browser/prefs/incognito_mode_prefs.cc
+++ b/chrome/browser/prefs/incognito_mode_prefs.cc
@@ -23,7 +23,17 @@
 #if defined(OS_WIN)
 namespace {
 
-bool g_parental_control_on = false;
+// Possible values for the parental controls state.
+enum class ParentalControlsState {
+  // Parental controls state unknown. We have not queried for this value yet.
+  UNKNOWN = 0,
+  // Parental controls activity logging disabled.
+  ACTIVITY_LOGGING_DISABLED = 1,
+  // Parental controls activity logging enabled.
+  ACTIVITY_LOGGING_ENABLED = 2,
+};
+ParentalControlsState g_parental_controls_state =
+    ParentalControlsState::UNKNOWN;
 
 } // empty namespace
 #endif  // OS_WIN
@@ -47,7 +57,7 @@ IncognitoModePrefs::Availability IncognitoModePrefs::GetAvailability(
   Availability result = IncognitoModePrefs::ENABLED;
   bool valid = IntToAvailability(pref_value, &result);
   DCHECK(valid);
-  if (ArePlatformParentalControlsEnabled()) {
+  if (ArePlatformParentalControlsEnabledCached()) {
     if (result == IncognitoModePrefs::FORCED)
       LOG(ERROR) << "Ignoring FORCED incognito. Parental control logging on";
     return IncognitoModePrefs::DISABLED;
@@ -101,28 +111,27 @@ bool IncognitoModePrefs::CanOpenBrowser(Profile* profile) {
   }
 }
 
-// static
-bool IncognitoModePrefs::ArePlatformParentalControlsEnabled() {
+void IncognitoModePrefs::InitializePlatformParentalControls() {
 #if defined(OS_WIN)
-  // Disable incognito mode windows if parental controls are on. This is only
-  // for Windows Vista and above.
-  return base::win::IsParentalControlActivityLoggingOn();
-#elif defined(OS_ANDROID)
-  return chrome::android::ChromiumApplication::AreParentalControlsEnabled();
-#else
-  return false;
-#endif
+  DCHECK(g_parental_controls_state == ParentalControlsState::UNKNOWN);
+  g_parental_controls_state =
+      base::win::IsParentalControlActivityLoggingOn() ?
+          ParentalControlsState::ACTIVITY_LOGGING_ENABLED :
+          ParentalControlsState::ACTIVITY_LOGGING_DISABLED;
+#endif  // defined(OS_WIN)
 }
 
+void IncognitoModePrefs::UninitializePlatformParentalControlsImpl() {
 #if defined(OS_WIN)
-void IncognitoModePrefs::InitializePlatformParentalControls() {
-  g_parental_control_on = base::win::IsParentalControlActivityLoggingOn();
+  g_parental_controls_state = ParentalControlsState::UNKNOWN;

[msw, 2015/02/28 01:05:33]

Why do tests have to do this? Will the system value actually change?

[robliao, 2015/02/28 01:16:31]

Turns out this state is shared between groups of test cases in a single process
(since this is a global).

This means if one test case initializes this, all other ones get the
initialization for free. Of course this means if you reorder the test cases or
run them in complete isolation, things will break. 

The cleanup here ensures the initialization only occurs once and tests that need
to do this will break if they don't perform the initialization.

+#endif  // defined(OS_WIN)
 }
-#endif // OS_WIN
 
 bool IncognitoModePrefs::ArePlatformParentalControlsEnabledCached() {
 #if defined(OS_WIN)
-  return g_parental_control_on;
+  DCHECK(g_parental_controls_state != ParentalControlsState::UNKNOWN);
+  return g_parental_controls_state ==
+      ParentalControlsState::ACTIVITY_LOGGING_ENABLED;
 #elif defined(OS_ANDROID)
   return chrome::android::ChromiumApplication::AreParentalControlsEnabled();
 #else