Bug 1489499 - Don't call gtk_header_bar_get_decoration_layout() to get titlebar layout, r=jhorak

We don't set gtk_header_bar_set_decoration_layout() so we don't need to query the layout
by gtk_header_bar_get_decoration_layout(). That means we don't need to create the GtkHeaderBar
at startup when titlebar rendering is disabled.

Also unify window/header bar construction at CreateHeaderBarWidget() and assert when the widgets
are already created.

Differential Revision: https://phabricator.services.mozilla.com/D5417

--HG--
extra : moz-landing-system : lando

widget/gtk/WidgetStyleCache.cpp

@@ -528,23 +528,31 @@ CreateNotebookWidget()
   return widget;
 }
 
-static GtkWidget*
+static void
 CreateHeaderBarWidget(WidgetNodeType aWidgetType)
 {
   MOZ_ASSERT(gtk_check_version(3, 10, 0) == nullptr,
              "GtkHeaderBar is only available on GTK 3.10+.");
+  MOZ_ASSERT(sWidgetStorage[aWidgetType] == nullptr,
+             "Header bar widget is already created!");
 
   static auto sGtkHeaderBarNewPtr = (GtkWidget* (*)())
     dlsym(RTLD_DEFAULT, "gtk_header_bar_new");
 
   GtkWidget* headerbar = sGtkHeaderBarNewPtr();
+  sWidgetStorage[aWidgetType] = headerbar;
+
   GtkWidget *window = gtk_window_new(GTK_WINDOW_POPUP);
   GtkStyleContext* style = gtk_widget_get_style_context(window);
 
   if (aWidgetType == MOZ_GTK_HEADER_BAR_MAXIMIZED) {
     gtk_style_context_add_class(style, "maximized");
+    MOZ_ASSERT(sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW_MAXIMIZED] == nullptr,
+               "Window widget is already created!");
     sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW_MAXIMIZED] = window;
   } else {
+    MOZ_ASSERT(sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW] == nullptr,
+               "Window widget is already created!");
     sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW] = window;
   }
 
@@ -571,8 +579,6 @@ CreateHeaderBarWidget(WidgetNodeType aWidgetType)
   // We need to fix titlebar size calculation to also include
   // titlebar button sizes. (Bug 1419442)
   gtk_style_context_add_class(style, "default-decoration");
-
-  return headerbar;
 }
 
 #define ICON_SCALE_VARIANTS 2
@@ -761,15 +767,8 @@ CreateHeaderBarButtons()
 static void
 CreateHeaderBar()
 {
-  MOZ_ASSERT(sWidgetStorage[MOZ_GTK_HEADER_BAR] == nullptr &&
-             sWidgetStorage[MOZ_GTK_HEADER_BAR_MAXIMIZED] == nullptr,
-             "Header bar widget is already created!");
-
-  sWidgetStorage[MOZ_GTK_HEADER_BAR] =
   CreateHeaderBarWidget(MOZ_GTK_HEADER_BAR);
-  sWidgetStorage[MOZ_GTK_HEADER_BAR_MAXIMIZED] =
   CreateHeaderBarWidget(MOZ_GTK_HEADER_BAR_MAXIMIZED);
-
   CreateHeaderBarButtons();
 }
 

widget/gtk/gtk3drawing.cpp

@@ -428,22 +428,10 @@ GetGtkHeaderBarButtonLayout(WidgetNodeType* aButtonLayout, int aMaxButtonNums)
   NS_ASSERTION(aMaxButtonNums >= TOOLBAR_BUTTONS,
                "Requested number of buttons is higher than storage capacity!");
 
-  static auto sGtkHeaderBarGetDecorationLayoutPtr =
-    (const gchar* (*)(GtkWidget*))
-    dlsym(RTLD_DEFAULT, "gtk_header_bar_get_decoration_layout");
-
   const gchar* decorationLayout = nullptr;
-  if (sGtkHeaderBarGetDecorationLayoutPtr) {
-      GtkWidget* headerBar = GetWidget(MOZ_GTK_HEADER_BAR);
-      decorationLayout = sGtkHeaderBarGetDecorationLayoutPtr(headerBar);
-      if (!decorationLayout) {
-          GtkSettings *settings = gtk_settings_get_for_screen(
-              gdk_screen_get_default());
-          g_object_get(settings, "gtk-decoration-layout",
-                       &decorationLayout,
-                       nullptr);
-      }
-  }
+  GtkSettings *settings =
+      gtk_settings_get_for_screen(gdk_screen_get_default());
+  g_object_get(settings, "gtk-decoration-layout", &decorationLayout, nullptr);
 
   // Use a default layout
   if (!decorationLayout) {