Make WebUI webview content script work with incognito.

chrome/browser/ui/webui/webui_webview_browsertest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/macros.h"
 #include "base/path_service.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "chrome/test/base/web_ui_browser_test.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
 
 class WebUIWebViewBrowserTest : public WebUIBrowserTest {
  public:
   WebUIWebViewBrowserTest() {}
 
@@ skipping 107 matching lines @@
       new base::StringValue(GetTestUrl("empty.html").spec())));
 }
 
 IN_PROC_BROWSER_TEST_F(WebUIWebViewBrowserTest, AddContentScriptWithCode) {
   ui_test_utils::NavigateToURL(browser(), GetWebViewEnabledWebUIURL());
 
   ASSERT_TRUE(WebUIBrowserTest::RunJavascriptAsyncTest(
       "testAddContentScriptWithCode",
       new base::StringValue(GetTestUrl("empty.html").spec())));
 }
+
+#if defined(OS_CHROMEOS)
+IN_PROC_BROWSER_TEST_F(WebUIWebViewBrowserTest, AddContentScriptIncognito) {

[Devlin, 2015/04/27 17:55:56]

Awesome.

Can you:
- Put a comment saying that, right now, we only have incognito WebUI on CrOS,
but that this should theoretically work for all platforms
- Check that this did indeed fail before this patch?

[Xi Han, 2015/04/27 18:17:48]

Added. Yes, I modified other tests, which are in incognito mode and navigate to
other url like chrome://about/, and let them navigate to chrome://chrome-signin,
they do failed.

+  Browser* incognito_browser = ui_test_utils::OpenURLOffTheRecord(
+      browser()->profile(), GetWebViewEnabledWebUIURL());
+
+  SetWebUIInstance(
+      incognito_browser->tab_strip_model()->GetActiveWebContents()->GetWebUI());
+
+  ASSERT_TRUE(WebUIBrowserTest::RunJavascriptAsyncTest(
+      "testAddContentScript",
+      new base::StringValue(GetTestUrl("empty.html").spec())));
+}
+#endif