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/browser/ui/browser.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.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/navigation_handle.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/notification_types.h"
 
 namespace {
 
 class NavigationNotificationObserver : public content::NotificationObserver {
  public:
   NavigationNotificationObserver()
@@ skipping 17 matching lines @@
   bool got_navigation() const { return got_navigation_; }
 
  private:
   content::NotificationRegistrar registrar_;
   int got_navigation_;
   int http_status_code_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationNotificationObserver);
 };
 
+class NavigationObserver : public content::WebContentsObserver {
+public:
+  enum NavigationResult {
+    NOT_FINISHED,
+    ERROR_PAGE,
+    NON_ERROR_PAGE,

[Dan Beam, 2016/08/30 21:35:17]

nit: NON_ERROR -> SUCCESS or something?

[Peter Kasting, 2016/08/30 21:55:55]

Eschew unnecessary obfuscation?

SUCCESS is a perfectly good "navigation result".  Done.

+  };
+
+  explicit NavigationObserver(content::WebContents* web_contents)
+      : WebContentsObserver(web_contents), navigation_result_(NOT_FINISHED) {}
+  ~NavigationObserver() override = default;
+
+  void DidFinishNavigation(
+      content::NavigationHandle* navigation_handle) override {
+    navigation_result_ =
+        navigation_handle->IsErrorPage() ? ERROR_PAGE : NON_ERROR_PAGE;
+  }
+
+  NavigationResult navigation_result() const { return navigation_result_; }
+
+  void Reset() { navigation_result_ = NOT_FINISHED; }
+
+ private:
+  NavigationResult navigation_result_;
+
+  DISALLOW_COPY_AND_ASSIGN(NavigationObserver);
+};
+
 }  // namespace
 
 typedef InProcessBrowserTest ChromeURLDataManagerTest;
 
 // 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
+  NavigationObserver observer(
+      browser()->tab_strip_model()->GetActiveWebContents());
+  ui_test_utils::NavigateToURL(
+      browser(), GURL("chrome://theme/IDR_SETTINGS_FAVICON"));
+  EXPECT_EQ(NavigationObserver::NON_ERROR_PAGE, observer.navigation_result());
+
+  // Unknown resource
+  observer.Reset();
+  ui_test_utils::NavigateToURL(
+      browser(), GURL("chrome://theme/IDR_ASDFGHJKL"));
+  EXPECT_EQ(NavigationObserver::ERROR_PAGE, observer.navigation_result());
+}
+
 // 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
+  NavigationObserver observer(
+      browser()->tab_strip_model()->GetActiveWebContents());
   ui_test_utils::NavigateToURL(
       browser(), GURL("chrome://theme/IDR_SETTINGS_FAVICON@2x"));
+  EXPECT_EQ(NavigationObserver::NON_ERROR_PAGE, observer.navigation_result());
 
+  // Unreasonably large scale
+  observer.Reset();
   ui_test_utils::NavigateToURL(
       browser(), GURL("chrome://theme/IDR_SETTINGS_FAVICON@99999x"));
+  EXPECT_EQ(NavigationObserver::NON_ERROR_PAGE, observer.navigation_result());
 }