Add a CustomSchemeHandler runtime flag to remove ENABLE(CUSTOM_SCHEME_HANDLER)

Source/modules/navigatorcontentutils/NavigatorContentUtilsClient.h

Index: Source/modules/navigatorcontentutils/NavigatorContentUtilsClient.h
diff --git a/Source/modules/navigatorcontentutils/NavigatorContentUtilsClient.h b/Source/modules/navigatorcontentutils/NavigatorContentUtilsClient.h
index 9d91db92e2b180503f0ac2b34ecece43009f501d..ba632e5545a280988387be296fe7a3031bc25072 100644
--- a/Source/modules/navigatorcontentutils/NavigatorContentUtilsClient.h
+++ b/Source/modules/navigatorcontentutils/NavigatorContentUtilsClient.h
@@ -37,7 +37,6 @@ public:
     virtual ~NavigatorContentUtilsClient() { }
     virtual void registerProtocolHandler(const String& scheme, const String& baseURL, const String& url, const String& title) = 0;
 
-#if ENABLE(CUSTOM_SCHEME_HANDLER)
     enum CustomHandlersState {
         CustomHandlersNew,
         CustomHandlersRegistered,
@@ -46,7 +45,6 @@ public:
 
     virtual CustomHandlersState isProtocolHandlerRegistered(const String& scheme, const String& baseURL, const String& url) = 0;
     virtual void unregisterProtocolHandler(const String& scheme, const String& baseURL, const String& url) = 0;
-#endif
 };
 
 void provideNavigatorContentUtilsTo(Page*, NavigatorContentUtilsClient*);