Browser+LibWeb+WebContent: Make the "Debug" menu work in multi-process

This patch adds an IPC call for debugging requests. It's stringly typed
and very simple, and allows us to easily implement all the features in
the Browser's Debug menu.

Userland/Services/WebContent/ClientConnection.cpp

@@ -28,11 +28,21 @@
 #include <AK/Debug.h>
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/SystemTheme.h>
+#include <LibJS/Heap/Heap.h>
+#include <LibJS/Runtime/VM.h>
+#include <LibWeb/DOM/Document.h>
+#include <LibWeb/Dump.h>
+#include <LibWeb/Layout/InitialContainingBlockBox.h>
+#include <LibWeb/Page/Frame.h>
 #include <WebContent/ClientConnection.h>
 #include <WebContent/PageHost.h>
 #include <WebContent/WebContentClientEndpoint.h>
 #include <pthread.h>
 
+namespace Web::DOM {
+extern JS::VM& main_thread_vm();
+}
+
 namespace WebContent {
 
 static HashMap<int, RefPtr<ClientConnection>> s_connections;
@@ -165,4 +175,37 @@ void ClientConnection::handle(const Messages::WebContentServer::KeyDown& message
     page().handle_keydown((KeyCode)message.key(), message.modifiers(), message.code_point());
 }
 
+void ClientConnection::handle(const Messages::WebContentServer::DebugRequest& message)
+{
+    if (message.request() == "dump-dom-tree") {
+        if (auto* doc = page().main_frame().document())
+            Web::dump_tree(*doc);
+    }
+
+    if (message.request() == "dump-layout-tree") {
+        if (auto* doc = page().main_frame().document()) {
+            if (auto* icb = doc->layout_node())
+                Web::dump_tree(*icb);
+        }
+    }
+
+    if (message.request() == "dump-style-sheets") {
+        if (auto* doc = page().main_frame().document()) {
+            for (auto& sheet : doc->style_sheets().sheets()) {
+                Web::dump_sheet(sheet);
+            }
+        }
+    }
+
+    if (message.request() == "collect-garbage") {
+        ::Web::DOM::main_thread_vm().heap().collect_garbage(JS::Heap::CollectionType::CollectGarbage, true);
+    }
+
+    if (message.request() == "set-line-box-borders") {
+        bool state = message.argument() == "on";
+        m_page_host->set_should_show_line_box_borders(state);
+        page().main_frame().set_needs_display(page().main_frame().viewport_rect());
+    }
+}
+
 }

Userland/Services/WebContent/ClientConnection.h

@@ -62,6 +62,7 @@ private:
     virtual void handle(const Messages::WebContentServer::KeyDown&) override;
     virtual void handle(const Messages::WebContentServer::AddBackingStore&) override;
     virtual void handle(const Messages::WebContentServer::RemoveBackingStore&) override;
+    virtual void handle(const Messages::WebContentServer::DebugRequest&) override;
 
     void flush_pending_paint_requests();
 

Userland/Services/WebContent/PageHost.cpp

@@ -93,6 +93,7 @@ void PageHost::paint(const Gfx::IntRect& content_rect, Gfx::Bitmap& target)
     painter.translate(-content_rect.x(), -content_rect.y());
 
     Web::PaintContext context(painter, palette(), Gfx::IntPoint());
+    context.set_should_show_line_box_borders(m_should_show_line_box_borders);
     context.set_viewport_rect(content_rect);
     layout_root->paint_all_phases(context);
 }

Userland/Services/WebContent/PageHost.h

@@ -48,6 +48,8 @@ public:
     void set_palette_impl(const Gfx::PaletteImpl&);
     void set_viewport_rect(const Gfx::IntRect&);
 
+    void set_should_show_line_box_borders(bool b) { m_should_show_line_box_borders = b; }
+
 private:
     // ^PageClient
     virtual bool is_multi_process() const override { return true; }
@@ -75,6 +77,7 @@ private:
     ClientConnection& m_client;
     NonnullOwnPtr<Web::Page> m_page;
     RefPtr<Gfx::PaletteImpl> m_palette_impl;
+    bool m_should_show_line_box_borders { false };
 };
 
 }

Userland/Services/WebContent/WebContentServer.ipc

@@ -18,4 +18,6 @@ endpoint WebContentServer = 89
     MouseUp(Gfx::IntPoint position, unsigned button, unsigned buttons, unsigned modifiers) =|
 
     KeyDown(i32 key, unsigned modifiers, u32 code_point) =|
+
+    DebugRequest(String request, String argument) =|
 }