Fix setWindowVisibility() being a no-op for OSR/windowless browsers

java/tests/junittests/CefBrowserWindowVisibilityTest.java

@@ -0,0 +1,53 @@
+// Copyright (c) 2026 The Chromium Embedded Framework Authors. All rights
+// reserved. Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+
+package tests.junittests;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import org.cef.browser.CefBrowser;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+// Regression coverage for native/CefBrowser_N.cpp's N_SetWindowVisibility:
+// previously the whole function body was gated on OS_MACOSX, and even there
+// only ran when windowed (the IsWindowRenderingDisabled() check was
+// backwards for that branch's intent) -- so on every platform, for every
+// OSR (windowless) browser, setWindowVisibility() silently did nothing.
+// Fixed by routing windowless browsers to CefBrowserHost::WasHidden()
+// instead, CEF's own signal to pause/resume rendering and GPU resource
+// usage for a browser with no native window.
+//
+// This is a smoke test (doesn't throw, browser stays usable) rather than a
+// direct assertion on paused/resumed rendering state, since that internal
+// state isn't observable from the Java side.
+@ExtendWith(TestSetupExtension.class)
+class CefBrowserWindowVisibilityTest {
+    private static final String TEST_URL = "http://test.com/window_visibility_test.html";
+
+    @Test
+    void setWindowVisibilityOnOsrBrowserDoesNotThrow() {
+        TestFrame frame = new TestFrame() {
+            @Override
+            protected void setupTest() {
+                addResource(TEST_URL, "<html><body>Visibility Test</body></html>", "text/html");
+                createBrowser(TEST_URL, true /* useOSR */);
+                super.setupTest();
+            }
+
+            @Override
+            public void onLoadingStateChange(CefBrowser browser, boolean isLoading,
+                    boolean canGoBack, boolean canGoForward) {
+                if (isLoading) return;
+                terminateTest();
+            }
+        };
+
+        frame.awaitCompletion();
+
+        CefBrowser browser = frame.browser_;
+        assertDoesNotThrow(() -> browser.setWindowVisibility(false));
+        assertDoesNotThrow(() -> browser.setWindowVisibility(true));
+    }
+}

native/CefBrowser_N.cpp

@@ -1542,12 +1542,21 @@ Java_org_cef_browser_CefBrowser_1N_N_1SetWindowVisibility(JNIEnv* env,
                                                           jobject obj,
                                                           jboolean visible) {
   CefRefPtr<CefBrowser> browser = JNI_GET_BROWSER_OR_RETURN(env, obj);
+  CefRefPtr<CefBrowserHost> host = browser->GetHost();
 
-#if defined(OS_MACOSX)
-  if (!browser->GetHost()->IsWindowRenderingDisabled()) {
-    util_mac::SetVisibility(browser->GetHost()->GetWindowHandle(),
-                            visible != JNI_FALSE);
+  // Windowless (OSR) browsers have no native window for the OS-level
+  // visibility toggle below -- CefBrowserHost::WasHidden() is CEF's own
+  // signal for this case (used to pause/resume rendering and GPU resource
+  // usage). Previously this whole function was a no-op for every OSR browser
+  // on every platform except this one macOS branch, and even that branch had
+  // the windowless check backwards (skipped exactly when windowless).
+  if (host->IsWindowRenderingDisabled()) {
+    host->WasHidden(visible == JNI_FALSE);
+    return;
   }
+
+#if defined(OS_MACOSX)
+  util_mac::SetVisibility(host->GetWindowHandle(), visible != JNI_FALSE);
 #endif
 }
 JNIEXPORT jdouble JNICALL