Missing `contentFrame` after cross-origin navigation with PlzNavigate + site isolation.

content/browser/frame_host/navigation_handle_impl_browsertest.cc

Index: content/browser/frame_host/navigation_handle_impl_browsertest.cc
diff --git a/content/browser/frame_host/navigation_handle_impl_browsertest.cc b/content/browser/frame_host/navigation_handle_impl_browsertest.cc
index ba1c812e470e081ec81e0cf068c26b7b2637463b..303bcb3e5cfeeef4f0a3e7f2054104dac8592dbc 100644
--- a/content/browser/frame_host/navigation_handle_impl_browsertest.cc
+++ b/content/browser/frame_host/navigation_handle_impl_browsertest.cc
@@ -808,6 +808,48 @@ IN_PROC_BROWSER_TEST_F(NavigationHandleImplBrowserTest,
   EXPECT_FALSE(installer.navigation_throttle());
 }
 
+IN_PROC_BROWSER_TEST_F(NavigationHandleImplBrowserTest,
+                       BugBaseline) {
+  const char kChildFrameId[] = "child0";
+  GURL main_url(embedded_test_server()->GetURL(
+      "a.com", "/frame_tree/page_with_one_frame.html"));
+  GURL allowed_subframe_url(embedded_test_server()->GetURL(
+      "a.com", "/title2.html"));
+
+  ASSERT_TRUE(NavigateToURL(shell(), main_url));
+  ASSERT_TRUE(NavigateIframeToURL(shell()->web_contents(), kChildFrameId,
+                                  allowed_subframe_url));
+  const char kScript[] =
+      "let f = document.getElementById(\"%s\");"
+      "window.domAutomationController.send(!!f.contentWindow);";
+  bool has_content_window = 0;
+  EXPECT_TRUE(ExecuteScriptAndExtractBool(
+      shell(), base::StringPrintf(kScript, kChildFrameId),
+      &has_content_window));
+  EXPECT_TRUE(has_content_window);
+}
+
+IN_PROC_BROWSER_TEST_F(NavigationHandleImplBrowserTest,
+                       BugRepro) {
+  const char kChildFrameId[] = "child0";
+  GURL main_url(embedded_test_server()->GetURL(
+      "a.com", "/frame_tree/page_with_one_frame.html"));
+  GURL allowed_subframe_url(embedded_test_server()->GetURL(
+      "a.com", "/cross-site/baz.com/title2.html"));
+
+  ASSERT_TRUE(NavigateToURL(shell(), main_url));
+  ASSERT_TRUE(NavigateIframeToURL(shell()->web_contents(), kChildFrameId,
+                                  allowed_subframe_url));
+  const char kScript[] =
+      "let f = document.getElementById(\"%s\");"
+      "window.domAutomationController.send(!!f.contentWindow);";
+  bool has_content_window = 0;
+  EXPECT_TRUE(ExecuteScriptAndExtractBool(
+      shell(), base::StringPrintf(kScript, kChildFrameId),
+      &has_content_window));
+  EXPECT_TRUE(has_content_window);
+}
+
 // Checks that the RequestContextType value is properly set for an form (POST).
 IN_PROC_BROWSER_TEST_F(NavigationHandleImplBrowserTest,
                        VerifyFormRequestContextType) {