Fix DCHECK in debug build when navigating to an unknown chrome://theme/ URL.

chrome/browser/ui/webui/chrome_url_data_manager_browsertest.cc

 // Copyright (c) 2011 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 "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/notification_registrar.h"
@@ skipping 39 matching lines @@
 
 // Makes sure navigating to the new tab page results in a http status code
 // of 200.
 IN_PROC_BROWSER_TEST_F(ChromeURLDataManagerTest, 200) {
   NavigationNotificationObserver observer;
   ui_test_utils::NavigateToURL(browser(), GURL(chrome::kChromeUINewTabURL));
   EXPECT_TRUE(observer.got_navigation());
   EXPECT_EQ(200, observer.http_status_code());
 }
 
+// Makes sure browser does not crash when navigating to an unknown resource.
+IN_PROC_BROWSER_TEST_F(ChromeURLDataManagerTest, UnknownResource) {
+  // Known resource
+  ui_test_utils::NavigateToURL(
+      browser(), GURL("chrome://theme/IDR_SETTINGS_FAVICON"));
+
+  // Unknown resource
+  ui_test_utils::NavigateToURL(
+      browser(), GURL("chrome://theme/IDR_ASDFGHJKL"));
+}
+
 // Makes sure browser does not crash when the resource scale is very large.
-IN_PROC_BROWSER_TEST_F(ChromeURLDataManagerTest, ResourceScaleTest) {
+IN_PROC_BROWSER_TEST_F(ChromeURLDataManagerTest, LargeResourceScale) {
+  // Valid scale
   ui_test_utils::NavigateToURL(
       browser(), GURL("chrome://theme/IDR_SETTINGS_FAVICON@2x"));
 
+  // Unreasonably large scale
   ui_test_utils::NavigateToURL(
       browser(), GURL("chrome://theme/IDR_SETTINGS_FAVICON@99999x"));
 }