Add the basic infrastructure for the Behavior feature type: BehaviorFeature and

chrome/browser/extensions/extension_browsertest.cc

Index: chrome/browser/extensions/extension_browsertest.cc
diff --git a/chrome/browser/extensions/extension_browsertest.cc b/chrome/browser/extensions/extension_browsertest.cc
index d1ec36bbe6f58e272ae6eac77f03a0c0720bb642..4a919932629d25450f0b36914bd479c0a9671218 100644
--- a/chrome/browser/extensions/extension_browsertest.cc
+++ b/chrome/browser/extensions/extension_browsertest.cc
@@ -234,7 +234,8 @@ ExtensionBrowserTest::LoadExtensionWithInstallParam(
     content::WindowedNotificationObserver load_signal(
         extensions::NOTIFICATION_EXTENSION_LOADED_DEPRECATED,
         content::Source<Profile>(profile()));
-    CHECK(!extensions::util::IsIncognitoEnabled(extension_id, profile()));
+    CHECK(!extensions::util::IsIncognitoEnabled(extension_id, profile()))
+        << extension_id << " is enabled in incognito, but shouldn't be";
 
     if (flags & kFlagEnableIncognito) {
       extensions::util::SetIsIncognitoEnabled(extension_id, profile(), true);