Bug 1574291 - Render restore button, not just icon, when drawing titlebar. r=stransky

And attach it to the maximized headerbar, not to the regular one. Breeze
styles the button with background-image rather than icon-source.

Differential Revision: https://phabricator.services.mozilla.com/D179389

widget/gtk/WidgetStyleCache.cpp

@@ -661,13 +661,13 @@ bool IsSolidCSDStyleUsed() {
 
 static void CreateHeaderBarButtons() {
   GtkWidget* headerBar = sWidgetStorage[MOZ_GTK_HEADER_BAR];
-  MOZ_ASSERT(headerBar != nullptr, "We're missing header bar widget!");
+  MOZ_ASSERT(headerBar, "We're missing header bar widget!");
 
   gint buttonSpacing = 6;
   g_object_get(headerBar, "spacing", &buttonSpacing, nullptr);
 
   GtkWidget* buttonBox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, buttonSpacing);
-  gtk_container_add(GTK_CONTAINER(GetWidget(MOZ_GTK_HEADER_BAR)), buttonBox);
+  gtk_container_add(GTK_CONTAINER(headerBar), buttonBox);
   // We support only LTR headerbar layout for now.
   gtk_style_context_add_class(gtk_widget_get_style_context(buttonBox),
                               GTK_STYLE_CLASS_LEFT);
@@ -686,7 +686,7 @@ static void CreateHeaderBarButtons() {
     CreateHeaderBarButton(buttonBox, MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE);
     // We don't pack "restore" headerbar button to box as it's an icon
     // placeholder. Pack it only to header bar to get correct style.
-    CreateHeaderBarButton(GetWidget(MOZ_GTK_HEADER_BAR),
+    CreateHeaderBarButton(GetWidget(MOZ_GTK_HEADER_BAR_MAXIMIZED),
                           MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE_RESTORE);
   }
   if (IsToolbarButtonEnabled(buttonLayout, activeButtons,
@@ -1163,11 +1163,6 @@ static GtkStyleContext* GetCssNodeStyleInternal(WidgetNodeType aNodeType) {
       GtkWidget* widget = GetWidget(MOZ_GTK_NOTEBOOK);
       return gtk_widget_get_style_context(widget);
     }
-    case MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE_RESTORE: {
-      NS_ASSERTION(
-          false, "MOZ_GTK_HEADER_BAR_BUTTON_RESTORE is used as an icon only!");
-      return nullptr;
-    }
     case MOZ_GTK_WINDOW_DECORATION: {
       GtkStyleContext* parentStyle =
           CreateSubStyleWithClass(MOZ_GTK_WINDOW, "csd");

widget/gtk/gtk3drawing.cpp

@@ -499,19 +499,16 @@ static gint moz_gtk_header_bar_button_paint(cairo_t* cr,
                                             GtkReliefStyle relief,
                                             WidgetNodeType aIconWidgetType,
                                             GtkTextDirection direction) {
-  WidgetNodeType buttonWidgetType =
-      (aIconWidgetType == MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE_RESTORE)
-          ? MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE
-          : aIconWidgetType;
-
   GdkRectangle rect = *aRect;
   // We need to inset our calculated margin because it also
   // contains titlebar button spacing.
-  const ToolbarButtonGTKMetrics* metrics =
-      GetToolbarButtonMetrics(buttonWidgetType);
+  const ToolbarButtonGTKMetrics* metrics = GetToolbarButtonMetrics(
+      aIconWidgetType == MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE_RESTORE
+          ? MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE
+          : aIconWidgetType);
   Inset(&rect, metrics->buttonMargin);
 
-  GtkWidget* buttonWidget = GetWidget(buttonWidgetType);
+  GtkWidget* buttonWidget = GetWidget(aIconWidgetType);
   if (!buttonWidget) {
     return MOZ_GTK_UNKNOWN_WIDGET;
   }
@@ -533,9 +530,6 @@ static gint moz_gtk_header_bar_button_paint(cairo_t* cr,
     StyleContextSetScale(style, state->image_scale);
     gtk_style_context_set_state(style, state_flags);
 
-    const ToolbarButtonGTKMetrics* metrics =
-        GetToolbarButtonMetrics(buttonWidgetType);
-
     /* This is available since Gtk+ 3.10 as well as GtkHeaderBar */
     gtk_render_icon_surface(style, cr, surface, rect.x + metrics->iconXPosition,
                             rect.y + metrics->iconYPosition);