Adds testing infrastructure to web_ui_browsertest to support testing HtmlDialogs.

chrome/chrome_tests.gypi

Index: chrome/chrome_tests.gypi
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 067b18c99fa19ebfed0d651b9eeedf2e15a661b1..0298cbe8ee5afa144437b489d7e371eee0107e40 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -194,6 +194,8 @@
         'test/base/ui_test_utils_win.cc',
         'test/base/values_test_util.cc',
         'test/base/values_test_util.h',
+        'test/test_html_dialog_observer.cc',
+        'test/test_html_dialog_observer.h',
         'test/test_navigation_observer.cc',
         'test/test_navigation_observer.h',
         # TODO:  these should live here but are currently used by
@@ -2424,6 +2426,7 @@
         'test/data/webui/assertions.js',
         'test/data/webui/async_gen-inl.h',
         'test/data/webui/async_gen.js',
+        'test/data/webui/certificate_viewer_dialog_test.js',
         'test/data/webui/ntp4.js',
         'test/data/webui/options.js',
         'test/data/webui/print_preview.js',