MacPDF: Introduce MacPDFWindowController

I'd like to add a sidebar, and NSSplitViewItem apparently isn't
accessibly in .xib files without contortions. So I want to move
to creating the window in code, and this is a step towards that.

No behavior change.

Meta/Lagom/Contrib/MacPDF/CMakeLists.txt

@@ -19,6 +19,7 @@ add_executable(MacPDF MACOSX_BUNDLE
     AppDelegate.mm
     MacPDFDocument.mm
     MacPDFView.mm
+    MacPDFWindowController.mm
 )
 target_compile_options(MacPDF PRIVATE
     -fobjc-arc

Meta/Lagom/Contrib/MacPDF/MacPDFDocument.mm

@@ -8,6 +8,7 @@
 
 #import <UniformTypeIdentifiers/UniformTypeIdentifiers.h>
 
+#import "MacPDFWindowController.h"
 #include <LibPDF/Document.h>
 
 @interface MacPDFDocument ()
@@ -71,9 +72,9 @@
     }
 }
 
-- (NSString*)windowNibName
+- (void)makeWindowControllers
 {
-    return @"MacPDFDocument";
+    [self addWindowController:[[MacPDFWindowController alloc] initWithDocument:self]];
 }
 
 - (void)windowControllerDidLoadNib:(NSWindowController*)aController

Meta/Lagom/Contrib/MacPDF/MacPDFWindowController.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2023, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "CocoaWrapper.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@class MacPDFDocument;
+
+@interface MacPDFWindowController : NSWindowController
+
+- (instancetype)initWithDocument:(MacPDFDocument*)document;
+
+@end
+
+NS_ASSUME_NONNULL_END

Meta/Lagom/Contrib/MacPDF/MacPDFWindowController.mm

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2023, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#import "MacPDFWindowController.h"
+
+@implementation MacPDFWindowController
+
+- (instancetype)initWithDocument:(MacPDFDocument*)document
+{
+    if (self = [super initWithWindowNibName:@"MacPDFDocument" owner:self]; !self)
+        return nil;
+
+    return self;
+}
+
+
+@end