DOMUI prefs: Add and wire up a stub overlay for adding a startup page.

BUG=49090
TEST=The "Add..." button on the Basics page of DOMUI options should bring up an empty overlay.

Review URL: http://codereview.chromium.org/3020021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@53479 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 5a5a262..7a87f00 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1078,6 +1078,8 @@
         'browser/dom_ui/bookmarks_ui.h',
         'browser/dom_ui/chrome_url_data_manager.cc',
         'browser/dom_ui/chrome_url_data_manager.h',
+        'browser/dom_ui/add_startup_page_handler.cc',
+        'browser/dom_ui/add_startup_page_handler.h',
         'browser/dom_ui/advanced_options_handler.cc',
         'browser/dom_ui/advanced_options_handler.h',
         'browser/dom_ui/advanced_options_utils_mac.mm',