Convert ExtensionLoaderHandler to use the new navigation callbacks.

chrome/browser/ui/webui/extensions/extension_loader_handler.h

 // Copyright 2014 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_EXTENSIONS_EXTENSION_LOADER_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_EXTENSIONS_EXTENSION_LOADER_HANDLER_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 47 matching lines @@
 
   // Try to load an unpacked extension from the given |file_path|.
   void LoadUnpackedExtension(const base::FilePath& file_path);
 
   // ExtensionErrorReporter::Observer:
   void OnLoadFailure(content::BrowserContext* browser_context,
                      const base::FilePath& file_path,
                      const std::string& error) override;
 
   // content::WebContentsObserver:
-  void DidStartNavigationToPendingEntry(
-      const GURL& url,
-      content::ReloadType reload_type) override;
+  void DidStartNavigation(
+      content::NavigationHandle* navigation_handle) override;
 
   // Add a failure to |failures_|. If it was a manifest error, |manifest| will
   // hold the manifest contents, and |line_number| will point to the line at
   // which the error was found.
   void AddFailure(const base::FilePath& file_path,
                   const std::string& error,
                   size_t line_number,
                   const std::string& manifest);
 
   // Notify the frontend of all failures.
@@ skipping 19 matching lines @@
 
   // Weak pointer factory for posting background tasks.
   base::WeakPtrFactory<ExtensionLoaderHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionLoaderHandler);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_UI_WEBUI_EXTENSIONS_EXTENSION_LOADER_HANDLER_H_