Make the resized flag atomic

On Android it's set on the Java UI thread right after writing g_display,
and read on the render thread, which then copies the dp size into the UI
bounds just once. With a plain bool the render thread could see the flag
before the new size.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

UI/NativeApp.cpp

@@ -33,6 +33,7 @@
 
 #include <clocale>
 #include <algorithm>
+#include <atomic>
 #include <cstdlib>
 #include <memory>
 #include <mutex>
@@ -184,7 +185,9 @@ void SaveFrameDump();
 ScreenManager *g_screenManager;
 std::string config_filename;
 
-static bool resized = false;
+// Set from any thread (on Android, the Java UI thread right after it writes g_display). Atomic, so the frame
+// that consumes it also sees those writes - with a plain bool it could see the flag first and keep stale bounds.
+static std::atomic<bool> resized{false};
 
 static int renderCounter = 0;
 
@@ -1157,10 +1160,9 @@ void NativeFrame(GraphicsContext *graphicsContext) {
 	}
 
 	// Resize before drawing anything, so the first frame at a new size isn't drawn into the old backbuffer.
-	const bool resizedThisFrame = resized;
-	if (resized) {
-		INFO_LOG(Log::G3D, "Resized flag set - recalculating bounds");
-		resized = false;
+	const bool resizedThisFrame = resized.exchange(false);
+	if (resizedThisFrame) {
+		INFO_LOG(Log::G3D, "Resized flag set - recalculating bounds (%dx%d dp)", g_display.dp_xres, g_display.dp_yres);
 
 		if (uiContext) {
 			uiContext->SetBounds(Bounds(0, 0, g_display.dp_xres, g_display.dp_yres));