LibWeb+WebContent: Add IPC flow for Inspect DOM Tree

Add `inspect_dom_tree` to WebContentServer and 'did_get_dom_tree' to
WebContentClient.

These two async methods form a request & response for requesting a JSON
representation of the Content's DOM tree.

Userland/Libraries/LibWeb/OutOfProcessWebView.cpp

@@ -335,6 +335,12 @@ void OutOfProcessWebView::notify_server_did_get_source(const URL& url, const Str
         on_get_source(url, source);
 }
 
+void OutOfProcessWebView::notify_server_did_get_dom_tree(const String& dom_tree)
+{
+    if (on_get_dom_tree)
+        on_get_dom_tree(dom_tree);
+}
+
 void OutOfProcessWebView::notify_server_did_js_console_output(const String& method, const String& line)
 {
     if (on_js_console_output)
@@ -391,6 +397,11 @@ void OutOfProcessWebView::get_source()
     client().async_get_source();
 }
 
+void OutOfProcessWebView::inspect_dom_tree()
+{
+    client().async_inspect_dom_tree();
+}
+
 void OutOfProcessWebView::js_console_initialize()
 {
     client().async_js_console_initialize();

Userland/Libraries/LibWeb/OutOfProcessWebView.h

@@ -31,6 +31,7 @@ public:
 
     void debug_request(const String& request, const String& argument = {});
     void get_source();
+    void inspect_dom_tree();
     void js_console_initialize();
     void js_console_input(const String& js_source);
 
@@ -57,6 +58,7 @@ public:
     bool notify_server_did_request_confirm(Badge<WebContentClient>, const String& message);
     String notify_server_did_request_prompt(Badge<WebContentClient>, const String& message, const String& default_);
     void notify_server_did_get_source(const URL& url, const String& source);
+    void notify_server_did_get_dom_tree(const String& dom_tree);
     void notify_server_did_js_console_output(const String& method, const String& line);
     void notify_server_did_change_favicon(const Gfx::Bitmap& favicon);
     String notify_server_did_request_cookie(Badge<WebContentClient>, const URL& url, Cookie::Source source);

Userland/Libraries/LibWeb/WebContentClient.cpp

@@ -136,6 +136,11 @@ void WebContentClient::did_get_source(URL const& url, String const& source)
     m_view.notify_server_did_get_source(url, source);
 }
 
+void WebContentClient::did_get_dom_tree(const String& dom_tree)
+{
+    m_view.notify_server_did_get_dom_tree(dom_tree);
+}
+
 void WebContentClient::did_js_console_output(String const& method, String const& line)
 {
     m_view.notify_server_did_js_console_output(method, line);

Userland/Libraries/LibWeb/WebContentClient.h

@@ -49,6 +49,7 @@ private:
     virtual void did_request_link_context_menu(Gfx::IntPoint const&, URL const&, String const&, unsigned) override;
     virtual void did_request_image_context_menu(Gfx::IntPoint const&, URL const&, String const&, unsigned, Gfx::ShareableBitmap const&) override;
     virtual void did_get_source(URL const&, String const&) override;
+    virtual void did_get_dom_tree(String const&) override;
     virtual void did_js_console_output(String const&, String const&) override;
     virtual void did_change_favicon(Gfx::ShareableBitmap const&) override;
     virtual void did_request_alert(String const&) override;

Userland/Libraries/LibWeb/WebViewHooks.h

@@ -27,6 +27,7 @@ public:
     Function<void(const URL&)> on_url_drop;
     Function<void(DOM::Document*)> on_set_document;
     Function<void(const URL&, const String&)> on_get_source;
+    Function<void(const String&)> on_get_dom_tree;
     Function<void(const String& method, const String& line)> on_js_console_output;
     Function<String(const URL& url, Cookie::Source source)> on_get_cookie;
     Function<void(const URL& url, const Cookie::ParsedCookie& cookie, Cookie::Source source)> on_set_cookie;

Userland/Services/WebContent/ClientConnection.cpp

@@ -6,6 +6,7 @@
 
 #include <AK/Badge.h>
 #include <AK/Debug.h>
+#include <AK/JsonObject.h>
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/FontDatabase.h>
 #include <LibGfx/SystemTheme.h>
@@ -216,6 +217,13 @@ void ClientConnection::get_source()
     }
 }
 
+void ClientConnection::inspect_dom_tree()
+{
+    if (auto* doc = page().top_level_browsing_context().document()) {
+        async_did_get_dom_tree(doc->dump_dom_tree_as_json());
+    }
+}
+
 void ClientConnection::js_console_initialize()
 {
     if (auto* document = page().top_level_browsing_context().document()) {

Userland/Services/WebContent/ClientConnection.h

@@ -48,6 +48,7 @@ private:
     virtual void remove_backing_store(i32) override;
     virtual void debug_request(String const&, String const&) override;
     virtual void get_source() override;
+    virtual void inspect_dom_tree() override;
     virtual void js_console_initialize() override;
     virtual void js_console_input(String const&) override;
 

Userland/Services/WebContent/WebContentClient.ipc

@@ -23,6 +23,7 @@ endpoint WebContentClient
     did_request_confirm(String message) => (bool result)
     did_request_prompt(String message, String default_) => (String response)
     did_get_source(URL url, String source) =|
+    did_get_dom_tree(String dom_tree) =|
     did_js_console_output(String method, String line) =|
     did_change_favicon(Gfx::ShareableBitmap favicon) =|
     did_request_cookie(URL url, u8 source) => (String cookie)

Userland/Services/WebContent/WebContentServer.ipc

@@ -22,6 +22,7 @@ endpoint WebContentServer
 
     debug_request(String request, String argument) =|
     get_source() =|
+    inspect_dom_tree() =|
     js_console_initialize() =|
     js_console_input(String js_source) =|
 }