LibWeb+WebContent: Spawn Worker processes from the chrome

Instead of spawning these processes from the WebContent process, we now
create them in the Browser chrome.

Part 1/N of "all processes are owned by the chrome".

Userland/Libraries/LibWebView/CMakeLists.txt

@@ -8,6 +8,7 @@ set(SOURCES
     InspectorClient.cpp
     RequestServerAdapter.cpp
     SearchEngine.cpp
+    SocketPair.cpp
     SourceHighlighter.cpp
     URL.cpp
     UserAgent.cpp

Userland/Libraries/LibWebView/Forward.h

@@ -21,6 +21,7 @@ class WebContentClient;
 struct Attribute;
 struct CookieStorageKey;
 struct SearchEngine;
+struct SocketPair;
 
 }
 

Userland/Libraries/LibWebView/OutOfProcessWebView.cpp

@@ -17,6 +17,7 @@
 #include <LibGfx/Palette.h>
 #include <LibGfx/SystemTheme.h>
 #include <LibWeb/Crypto/Crypto.h>
+#include <LibWeb/Worker/WebWorkerClient.h>
 
 REGISTER_WIDGET(WebView, OutOfProcessWebView)
 
@@ -71,6 +72,11 @@ OutOfProcessWebView::OutOfProcessWebView()
     on_finish_handling_input_event = [this](auto event_was_accepted) {
         did_finish_handling_input_event(event_was_accepted);
     };
+
+    on_request_worker_agent = []() {
+        auto worker_client = MUST(Web::HTML::WebWorkerClient::try_create());
+        return worker_client->dup_sockets();
+    };
 }
 
 OutOfProcessWebView::~OutOfProcessWebView() = default;

Userland/Libraries/LibWebView/SocketPair.cpp

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibIPC/Decoder.h>
+#include <LibIPC/Encoder.h>
+#include <LibWebView/SocketPair.h>
+
+template<>
+ErrorOr<void> IPC::encode(Encoder& encoder, WebView::SocketPair const& pair)
+{
+    TRY(encoder.encode(pair.socket));
+    TRY(encoder.encode(pair.fd_passing_socket));
+    return {};
+}
+
+template<>
+ErrorOr<WebView::SocketPair> IPC::decode(Decoder& decoder)
+{
+    auto socket = TRY(decoder.decode<IPC::File>());
+    auto fd_passing_socket = TRY(decoder.decode<IPC::File>());
+
+    return WebView::SocketPair { move(socket), move(fd_passing_socket) };
+}

Userland/Libraries/LibWebView/SocketPair.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibIPC/File.h>
+
+namespace WebView {
+
+struct SocketPair {
+    IPC::File socket;
+    IPC::File fd_passing_socket;
+};
+
+}
+
+namespace IPC {
+
+template<>
+ErrorOr<void> encode(Encoder&, WebView::SocketPair const&);
+
+template<>
+ErrorOr<WebView::SocketPair> decode(Decoder&);
+
+}

Userland/Libraries/LibWebView/ViewImplementation.h

@@ -177,6 +177,7 @@ public:
     Function<void(i32, String const&, Vector<Attribute> const&)> on_inspector_replaced_dom_node_attribute;
     Function<void(i32, Gfx::IntPoint, String const&, Optional<String> const&, Optional<Attribute> const&)> on_inspector_requested_dom_tree_context_menu;
     Function<void(String const&)> on_inspector_executed_console_script;
+    Function<SocketPair()> on_request_worker_agent;
 
     virtual Web::DevicePixelRect viewport_rect() const = 0;
     virtual Gfx::IntPoint to_content_position(Gfx::IntPoint widget_position) const = 0;

Userland/Libraries/LibWebView/WebContentClient.cpp

@@ -478,4 +478,12 @@ void WebContentClient::inspector_did_execute_console_script(String const& script
         m_view.on_inspector_executed_console_script(script);
 }
 
+Messages::WebContentClient::RequestWorkerAgentResponse WebContentClient::request_worker_agent()
+{
+    if (m_view.on_request_worker_agent)
+        return m_view.on_request_worker_agent();
+
+    return Messages::WebContentClient::RequestWorkerAgentResponse { WebView::SocketPair { -1, -1 } };
+}
+
 }

Userland/Libraries/LibWebView/WebContentClient.h

@@ -98,6 +98,7 @@ private:
     virtual void inspector_did_replace_dom_node_attribute(i32 node_id, String const& name, Vector<Attribute> const& replacement_attributes) override;
     virtual void inspector_did_request_dom_tree_context_menu(i32 node_id, Gfx::IntPoint position, String const& type, Optional<String> const& tag, Optional<Attribute> const& attribute) override;
     virtual void inspector_did_execute_console_script(String const& script) override;
+    virtual Messages::WebContentClient::RequestWorkerAgentResponse request_worker_agent() override;
 
     ViewImplementation& m_view;
 };