Convert the external extension ui_test to a browser_test.

chrome/chrome_tests.gypi

Index: chrome/chrome_tests.gypi
===================================================================
--- chrome/chrome_tests.gypi	(revision 132499)
+++ chrome/chrome_tests.gypi	(working copy)
@@ -777,7 +777,6 @@
         'browser/ui/webui/options2/options_ui2_uitest.h',
         'browser/ui/webui/print_preview/print_preview_ui_uitest.cc',
         'common/logging_chrome_uitest.cc',
-        'renderer/external_extension_uitest.cc',
         'renderer/loadtimes_extension_bindings_uitest.cc',
         'test/automation/automation_proxy_uitest.cc',
         'test/automation/automation_proxy_uitest.h',
@@ -2871,6 +2870,7 @@
         'browser/extensions/system/system_apitest.cc',
         'browser/extensions/webstore_inline_install_browsertest.cc',
         'browser/extensions/window_open_apitest.cc',
+        'browser/external_extension_browsertest.cc',
         'browser/fast_shutdown_browsertest.cc',
         'browser/first_run/first_run_browsertest.cc',
         'browser/first_run/try_chrome_dialog_view_browsertest.cc',