Bug 1667851 [Wayland] Guess subsurface offset from window decorations size, r=jhorak

- Try to set subsurface offset even if we mozcontainer size allocation is not finished. Use window decoration size for it.
- Add more logging to mozcontainer code.

Depends on D104549

Differential Revision: https://phabricator.services.mozilla.com/D104550

widget/gtk/nsWindow.cpp

@@ -1072,13 +1072,26 @@ void nsWindow::SetSizeConstraints(const SizeConstraints& aConstraints) {
 }
 
 void nsWindow::AddCSDDecorationSize(int* aWidth, int* aHeight) {
-  if (mCSDSupportLevel == GTK_DECORATION_CLIENT && mDrawInTitlebar) {
+  if (mSizeState == nsSizeMode_Normal &&
+      mCSDSupportLevel == GTK_DECORATION_CLIENT && mDrawInTitlebar) {
     GtkBorder decorationSize = GetCSDDecorationSize(!mIsTopLevel);
     *aWidth += decorationSize.left + decorationSize.right;
     *aHeight += decorationSize.top + decorationSize.bottom;
   }
 }
 
+bool nsWindow::GetCSDDecorationOffset(int* aDx, int* aDy) {
+  if (mSizeState == nsSizeMode_Normal &&
+      mCSDSupportLevel == GTK_DECORATION_CLIENT && mDrawInTitlebar) {
+    GtkBorder decorationSize = GetCSDDecorationSize(!mIsTopLevel);
+    *aDx = decorationSize.left;
+    *aDy = decorationSize.top;
+    return true;
+  } else {
+    return false;
+  }
+}
+
 void nsWindow::ApplySizeConstraints(void) {
   if (mShell) {
     GdkGeometry geometry;