Fix navigation of chrome://oobe/login.

tools/telemetry/telemetry/core/chrome/browser_backend.py

Index: tools/telemetry/telemetry/core/chrome/browser_backend.py
===================================================================
--- tools/telemetry/telemetry/core/chrome/browser_backend.py	(revision 194990)
+++ tools/telemetry/telemetry/core/chrome/browser_backend.py	(working copy)
@@ -17,6 +17,7 @@
 from telemetry.core.chrome import extension_dict_backend
 from telemetry.core.chrome import tab_list_backend
 from telemetry.core.chrome import tracing_backend
+from telemetry.core.chrome import misc_web_contents_backend
 from telemetry.test import options_for_unittests
 
 class ExtensionsNotSupportedException(Exception):
@@ -51,11 +52,13 @@
                        'unexpected effects due to profile-specific settings, '
                        'such as about:flags settings, cookies, and '
                        'extensions.\n')
+    self._misc_web_contents_backend = (
+        misc_web_contents_backend.MiscWebContentsBackend(self))
     self._tab_list_backend = tab_list_backend.TabListBackend(self)
     self._extension_dict_backend = None
     if supports_extensions:
-      self._extension_dict_backend = \
-          extension_dict_backend.ExtensionDictBackend(self)
+      self._extension_dict_backend = (
+          extension_dict_backend.ExtensionDictBackend(self))
 
   def SetBrowser(self, browser):
     self._browser = browser
@@ -71,6 +74,12 @@
     return self._supports_extensions
 
   @property
+  def misc_web_contents_backend(self):
+    """Access to chrome://oobe/login page which is neither a tab nor an
+    extension."""
+    return self._misc_web_contents_backend
+
+  @property
   def tab_list_backend(self):
     return self._tab_list_backend