LibWeb+WebDriver: Add a flag to default WebDriver to headless mode

We previously only supported enabling headless mode on a per-session
basis via the capabilities record. We don't have the ability to mutate
this record from WPT, so this adds a flag to set the default mode.

Ladybird/WebDriver/main.cpp

@@ -14,6 +14,7 @@
 #include <LibCore/System.h>
 #include <LibCore/TCPServer.h>
 #include <LibMain/Main.h>
+#include <LibWeb/WebDriver/Capabilities.h>
 #include <WebDriver/Client.h>
 
 static Vector<ByteString> certificates;
@@ -74,12 +75,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto listen_address = "0.0.0.0"sv;
     int port = 8000;
     bool force_cpu_painting = false;
+    bool headless = false;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(listen_address, "IP address to listen on", "listen-address", 'l', "listen_address");
     args_parser.add_option(port, "Port to listen on", "port", 'p', "port");
     args_parser.add_option(certificates, "Path to a certificate file", "certificate", 'C', "certificate");
     args_parser.add_option(force_cpu_painting, "Launch browser with GPU painting disabled", "force-cpu-painting");
+    args_parser.add_option(headless, "Launch browser without a graphical interface", "headless");
     args_parser.parse(arguments);
 
     auto ipv4_address = IPv4Address::from_string(listen_address);
@@ -95,6 +98,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     platform_init();
 
+    Web::WebDriver::set_default_interface_mode(headless ? Web::WebDriver::InterfaceMode::Headless : Web::WebDriver::InterfaceMode::Graphical);
+
     auto webdriver_socket_path = ByteString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
     TRY(Core::Directory::create(webdriver_socket_path, Core::Directory::CreateDirectories::Yes));
 

Userland/Libraries/LibWeb/WebDriver/Capabilities.cpp

@@ -72,6 +72,13 @@ static ErrorOr<JsonObject, Error> deserialize_as_a_proxy(JsonValue parameter)
     return proxy;
 }
 
+static InterfaceMode default_interface_mode { InterfaceMode::Graphical };
+
+void set_default_interface_mode(InterfaceMode interface_mode)
+{
+    default_interface_mode = interface_mode;
+}
+
 static Response deserialize_as_ladybird_options(JsonValue value)
 {
     if (!value.is_object())
@@ -88,7 +95,7 @@ static Response deserialize_as_ladybird_options(JsonValue value)
 static JsonObject default_ladybird_options()
 {
     JsonObject options;
-    options.set("headless"sv, false);
+    options.set("headless"sv, default_interface_mode == InterfaceMode::Headless);
 
     return options;
 }

Userland/Libraries/LibWeb/WebDriver/Capabilities.h

@@ -54,6 +54,12 @@ constexpr UnhandledPromptBehavior unhandled_prompt_behavior_from_string(StringVi
     VERIFY_NOT_REACHED();
 }
 
+enum class InterfaceMode {
+    Graphical,
+    Headless,
+};
+void set_default_interface_mode(InterfaceMode);
+
 struct LadybirdOptions {
     explicit LadybirdOptions(JsonObject const& capabilities);