[macOS] Consolidate FlutterViewController static types/data

shell/platform/darwin/macos/framework/Source/FlutterViewController.mm

@@ -19,6 +19,8 @@
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterView.h"
 #import "flutter/shell/platform/embedder/embedder.h"
 
+#pragma mark - Static types and data.
+
 namespace {
 using flutter::KeyboardLayoutNotifier;
 using flutter::LayoutClue;
@@ -131,27 +133,6 @@ void Reset() {
   }
 };
 
-/**
- * Returns the current Unicode layout data (kTISPropertyUnicodeKeyLayoutData).
- *
- * To use the returned data, convert it to CFDataRef first, finds its bytes
- * with CFDataGetBytePtr, then reinterpret it into const UCKeyboardLayout*.
- * It's returned in NSData* to enable auto reference count.
- */
-NSData* currentKeyboardLayoutData() {
-  TISInputSourceRef source = TISCopyCurrentKeyboardInputSource();
-  CFTypeRef layout_data = TISGetInputSourceProperty(source, kTISPropertyUnicodeKeyLayoutData);
-  if (layout_data == nil) {
-    CFRelease(source);
-    // TISGetInputSourceProperty returns null with Japanese keyboard layout.
-    // Using TISCopyCurrentKeyboardLayoutInputSource to fix NULL return.
-    // https://github.com/microsoft/node-native-keymap/blob/5f0699ded00179410a14c0e1b0e089fe4df8e130/src/keyboard_mac.mm#L91
-    source = TISCopyCurrentKeyboardLayoutInputSource();
-    layout_data = TISGetInputSourceProperty(source, kTISPropertyUnicodeKeyLayoutData);
-  }
-  return (__bridge_transfer NSData*)CFRetain(layout_data);
-}
-
 }  // namespace
 
 #pragma mark - Private interface declaration.
@@ -249,22 +230,21 @@ - (void)onKeyboardLayoutChanged;
 
 @end
 
-#pragma mark - Private dependant functions
+#pragma mark - FlutterViewWrapper implementation.
 
-namespace {
-void OnKeyboardLayoutChanged(CFNotificationCenterRef center,
-                             void* observer,
-                             CFStringRef name,
-                             const void* object,
-                             CFDictionaryRef userInfo) {
+/**
+ * NotificationCenter callback invoked on kTISNotifySelectedKeyboardInputSourceChanged events.
+ */
+static void OnKeyboardLayoutChanged(CFNotificationCenterRef center,
+                                    void* observer,
+                                    CFStringRef name,
+                                    const void* object,
+                                    CFDictionaryRef userInfo) {
   FlutterViewController* controller = (__bridge FlutterViewController*)observer;
   if (controller != nil) {
     [controller onKeyboardLayoutChanged];
   }
 }
-}  // namespace
-
-#pragma mark - FlutterViewWrapper implementation.
 
 @implementation FlutterViewWrapper {
   FlutterView* _flutterView;
@@ -902,6 +882,27 @@ - (NSObject*)valuePublishedByPlugin:(NSString*)pluginKey {
 
 #pragma mark - FlutterKeyboardViewDelegate
 
+/**
+ * Returns the current Unicode layout data (kTISPropertyUnicodeKeyLayoutData).
+ *
+ * To use the returned data, convert it to CFDataRef first, finds its bytes
+ * with CFDataGetBytePtr, then reinterpret it into const UCKeyboardLayout*.
+ * It's returned in NSData* to enable auto reference count.
+ */
+static NSData* CurrentKeyboardLayoutData() {
+  TISInputSourceRef source = TISCopyCurrentKeyboardInputSource();
+  CFTypeRef layout_data = TISGetInputSourceProperty(source, kTISPropertyUnicodeKeyLayoutData);
+  if (layout_data == nil) {
+    CFRelease(source);
+    // TISGetInputSourceProperty returns null with Japanese keyboard layout.
+    // Using TISCopyCurrentKeyboardLayoutInputSource to fix NULL return.
+    // https://github.com/microsoft/node-native-keymap/blob/5f0699ded00179410a14c0e1b0e089fe4df8e130/src/keyboard_mac.mm#L91
+    source = TISCopyCurrentKeyboardLayoutInputSource();
+    layout_data = TISGetInputSourceProperty(source, kTISPropertyUnicodeKeyLayoutData);
+  }
+  return (__bridge_transfer NSData*)CFRetain(layout_data);
+}
+
 - (void)sendKeyEvent:(const FlutterKeyEvent&)event
             callback:(nullable FlutterKeyEventCallback)callback
             userData:(nullable void*)userData {
@@ -922,7 +923,7 @@ - (void)subscribeToKeyboardLayoutChange:(nullable KeyboardLayoutNotifier)callbac
 
 - (LayoutClue)lookUpLayoutForKeyCode:(uint16_t)keyCode shift:(BOOL)shift {
   if (_keyboardLayoutData == nil) {
-    _keyboardLayoutData = currentKeyboardLayoutData();
+    _keyboardLayoutData = CurrentKeyboardLayoutData();
   }
   const UCKeyboardLayout* layout = reinterpret_cast<const UCKeyboardLayout*>(
       CFDataGetBytePtr((__bridge CFDataRef)_keyboardLayoutData));