Implement chrome.systemPrivate.getIncognitoModeAvailability extension API function

chrome/browser/extensions/extension_preference_apitest.cc

Index: chrome/browser/extensions/extension_preference_apitest.cc
diff --git a/chrome/browser/extensions/extension_preference_apitest.cc b/chrome/browser/extensions/extension_preference_apitest.cc
index 642cd7ba40981566e0fba9687b3d407a0ade795e..bc74adae9d9dc9bc54bf3b1328212836f6f9a0de 100644
--- a/chrome/browser/extensions/extension_preference_apitest.cc
+++ b/chrome/browser/extensions/extension_preference_apitest.cc
@@ -26,6 +26,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PreferenceApi) {
   pref_service->SetBoolean(prefs::kNetworkPredictionEnabled, false);
   pref_service->SetBoolean(prefs::kSafeBrowsingEnabled, false);
   pref_service->SetBoolean(prefs::kSearchSuggestEnabled, false);
+  pref_service->SetInteger(prefs::kIncognitoModeAvailability, 1);
 
   EXPECT_TRUE(RunExtensionTest("preference/standard")) << message_;
 
@@ -43,6 +44,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PreferenceApi) {
   EXPECT_TRUE(pref_service->GetBoolean(prefs::kNetworkPredictionEnabled));
   EXPECT_TRUE(pref_service->GetBoolean(prefs::kSafeBrowsingEnabled));
   EXPECT_TRUE(pref_service->GetBoolean(prefs::kSearchSuggestEnabled));
+  EXPECT_EQ(1, pref_service->GetInteger(prefs::kIncognitoModeAvailability));
 }
 
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, PreferencePersistentIncognito) {