Bug 1777664 [Linux] Don't pause/resume compositor by nsWindow::SetCom…

…positorWidgetDelegate() r=emilio

nsWindow::SetCompositorWidgetDelegate() should not control compositor state as nsWindow::SetCompositorWidgetDelegate() itself is called by nsBaseWidget::CreateCompositor()/nsBaseWidget::DestroyCompositor().

In this patch we remove compositor pause/resume from nsWindow::SetCompositorWidgetDelegate() and update only GdkWindow/XWindow stored in remote widget.

Differential Revision: https://phabricator.services.mozilla.com/D152687

widget/gtk/nsWindow.cpp

@@ -5303,11 +5303,6 @@ static void GtkWidgetDisableUpdates(GtkWidget* aWidget) {
 void nsWindow::EnableRenderingToWindow() {
   LOG("nsWindow::EnableRenderingToWindow()");
 
-  if (mCompositorWidgetDelegate) {
-    mCompositorWidgetDelegate->EnableRendering(GetX11Window(),
-                                               GetShapedState());
-  }
-
   if (GdkIsWaylandDisplay()) {
 #ifdef MOZ_WAYLAND
     moz_container_wayland_add_initial_draw_callback(
@@ -5417,6 +5412,11 @@ void nsWindow::ConfigureGdkWindow() {
     mCompositorState = COMPOSITOR_PAUSED_MISSING_WINDOW;
   }
 
+  if (mCompositorWidgetDelegate) {
+    mCompositorWidgetDelegate->EnableRendering(GetX11Window(),
+                                               GetShapedState());
+  }
+
   EnableRenderingToWindow();
 
   if (mHasMappedToplevel) {
@@ -8503,26 +8503,29 @@ void nsWindow::DidGetNonBlankPaint() {
 /* nsWindow::SetCompositorWidgetDelegate() sets remote GtkCompositorWidget
  * to render into with compositor.
  *
- * If we're already visible we need to recreate compositor/vsync state.
+ * SetCompositorWidgetDelegate(delegate) is called from
+ * nsBaseWidget::CreateCompositor(), i.e. nsWindow::GetWindowRenderer().
+ *
+ * SetCompositorWidgetDelegate(null) is called from
+ * nsBaseWidget::DestroyCompositor().
  */
 void nsWindow::SetCompositorWidgetDelegate(CompositorWidgetDelegate* delegate) {
   LOG("nsWindow::SetCompositorWidgetDelegate %p\n", delegate);
 
-  // There's a change of remote widget - stop compositor and VSync as
-  // we're going re-init it.
-  if (mCompositorWidgetDelegate && mIsMapped) {
-    DisableRenderingToWindow();
+  // Remove reference to GdkWindow/XWindow from remote widget.
+  if (mCompositorWidgetDelegate) {
+    mCompositorWidgetDelegate->DisableRendering();
   }
 
   if (delegate) {
     mCompositorWidgetDelegate = delegate->AsPlatformSpecificDelegate();
     MOZ_ASSERT(mCompositorWidgetDelegate,
                "nsWindow::SetCompositorWidgetDelegate called with a "
                "non-PlatformCompositorWidgetDelegate");
-    // This is called from nsBaseWidget::CreateCompositor() in which case
-    // we need to create a new EGL surface in RenderCompositorEGL on X11
+    // Pass recent GdkWindow/XWindow to remote widget.
     if (mIsMapped) {
-      EnableRenderingToWindow();
+      mCompositorWidgetDelegate->EnableRendering(GetX11Window(),
+                                                 GetShapedState());
     }
   } else {
     mCompositorWidgetDelegate = nullptr;