Add a test for DevTools extensions on OTR NTP

Upstream fix: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2216940

Bug: 1085228
Change-Id: I641542cd65f18a573a291a7e3f0feebce7b69ea3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2216708
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772482}

chrome/browser/devtools/devtools_sanity_browsertest.cc

@@ -36,6 +36,7 @@
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/extension_util.h"
 #include "chrome/browser/extensions/unpacked_installer.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/browser/lifetime/browser_shutdown.h"
@@ -256,6 +257,14 @@ class DevToolsSanityTest : public InProcessBrowserTest {
                                                             is_docked);
   }
 
+  void OpenDevToolsWindowOnOffTheRecordTab(const std::string& test_page) {
+    GURL url = spawned_test_server()->GetURL("").Resolve(test_page);
+    auto* otr_browser = OpenURLOffTheRecord(browser()->profile(), url);
+
+    window_ = DevToolsWindowTesting::OpenDevToolsWindowSync(
+        otr_browser->tab_strip_model()->GetWebContentsAt(0), false);
+  }
+
   WebContents* GetInspectedTab() {
     return browser()->tab_strip_model()->GetWebContentsAt(0);
   }
@@ -852,6 +861,25 @@ IN_PROC_BROWSER_TEST_F(DevToolsExtensionTest,
   RunTest("waitForTestResultsInConsole", std::string());
 }
 
+// Tests that chrome.devtools extension is correctly exposed.
+IN_PROC_BROWSER_TEST_F(DevToolsExtensionTest, TestExtensionOnNewTab) {
+  // Not really required by this test, but the underlying code happens
+  // to expect it.
+  ASSERT_TRUE(embedded_test_server()->Start());
+  // Install the dynamically-generated devtools extension.
+  const Extension* devtools_extension = LoadExtensionForTest(
+      "Devtools Extension", "panel_devtools_page.html", "");
+  ASSERT_TRUE(devtools_extension);
+  extensions::util::SetIsIncognitoEnabled(devtools_extension->id(),
+                                          browser()->profile(), true);
+
+  OpenDevToolsWindowOnOffTheRecordTab(chrome::kChromeUINewTabURL);
+
+  // Wait for the extension's panel to finish loading -- it'll output 'PASS'
+  // when it's installed. waitForTestResultsInConsole waits until that 'PASS'.
+  RunTestFunction(window_, "waitForTestResultsInConsole");
+}
+
 // Tests that http Iframes within the visible devtools panel for the devtools
 // extension are rendered in their own processes and not in the devtools process
 // or the extension's process.  This is tested because this is one of the