[Input View] avoid crash when set override url for virtual keyboard window.

BUG=337768
TEST=Verified in sandbox.

Review URL: https://codereview.chromium.org/139123003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247122 0039d316-1c4b-4281-b951-d872f2087c98
cros: Disable ProxyAuthDialogOnSigninScreen.

BUG=338087
TBR=bartfab@chromium.org

Review URL: https://codereview.chromium.org/147633003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247123 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247123