LibJS+LibWebView+WebContent+Ladybird: Output GC-graph into a file

Instead of displaying a massive JSON in stdout, it's more practical
to save the GC-graph to a file.

Userland/Libraries/LibJS/Heap/Heap.cpp

@@ -192,7 +192,7 @@ public:
         }
     }
 
-    void dump()
+    AK::JsonObject dump()
     {
         auto graph = AK::JsonObject();
         for (auto& it : m_graph) {
@@ -233,7 +233,7 @@ public:
             graph.set(DeprecatedString::number(it.key), node);
         }
 
-        dbgln("{}", graph.to_deprecated_string());
+        return graph;
     }
 
 private:
@@ -253,14 +253,14 @@ private:
     FlatPtr m_max_block_address;
 };
 
-void Heap::dump_graph()
+AK::JsonObject Heap::dump_graph()
 {
     HashMap<Cell*, HeapRoot> roots;
     gather_roots(roots);
     GraphConstructorVisitor visitor(*this, roots);
     vm().bytecode_interpreter().visit_edges(visitor);
     visitor.visit_all_cells();
-    visitor.dump();
+    return visitor.dump();
 }
 
 void Heap::collect_garbage(CollectionType collection_type, bool print_report)

Userland/Libraries/LibJS/Heap/Heap.h

@@ -64,7 +64,7 @@ public:
     };
 
     void collect_garbage(CollectionType = CollectionType::CollectGarbage, bool print_report = false);
-    void dump_graph();
+    AK::JsonObject dump_graph();
 
     bool should_collect_on_every_allocation() const { return m_should_collect_on_every_allocation; }
     void set_should_collect_on_every_allocation(bool b) { m_should_collect_on_every_allocation = b; }

Userland/Libraries/LibWebView/ViewImplementation.cpp

@@ -403,8 +403,8 @@ static ErrorOr<LexicalPath> save_screenshot(Gfx::ShareableBitmap const& bitmap)
 
     auto encoded = TRY(Gfx::PNGWriter::encode(*bitmap.bitmap()));
 
-    auto screenshot_file = TRY(Core::File::open(path.string(), Core::File::OpenMode::Write));
-    TRY(screenshot_file->write_until_depleted(encoded));
+    auto dump_file = TRY(Core::File::open(path.string(), Core::File::OpenMode::Write));
+    TRY(dump_file->write_until_depleted(encoded));
 
     return path;
 }
@@ -432,6 +432,19 @@ ErrorOr<LexicalPath> ViewImplementation::take_dom_node_screenshot(i32 node_id)
     return save_screenshot(bitmap);
 }
 
+ErrorOr<LexicalPath> ViewImplementation::dump_gc_graph()
+{
+    auto gc_graph_json = client().dump_gc_graph();
+
+    LexicalPath path { Core::StandardPaths::tempfile_directory() };
+    path = path.append(TRY(Core::DateTime::now().to_string("gc-graph-%Y-%m-%d-%H-%M-%S.json"sv)));
+
+    auto screenshot_file = TRY(Core::File::open(path.string(), Core::File::OpenMode::Write));
+    TRY(screenshot_file->write_until_depleted(gc_graph_json.bytes()));
+
+    return path;
+}
+
 void ViewImplementation::set_user_style_sheet(String source)
 {
     client().async_set_user_style(move(source));

Userland/Libraries/LibWebView/ViewImplementation.h

@@ -99,6 +99,8 @@ public:
     ErrorOr<LexicalPath> take_screenshot(ScreenshotType);
     ErrorOr<LexicalPath> take_dom_node_screenshot(i32);
 
+    ErrorOr<LexicalPath> dump_gc_graph();
+
     void set_user_style_sheet(String source);
     // Load Native.css as the User style sheet, which attempts to make WebView content look as close to
     // native GUI widgets as possible.