Allow to specify elide behavior for confrim infobar message

Used in "<extension name> is debugging this browser" infobar.

Bug: 823194
Change-Id: Iff6627097c020cccca8f7cc3e21a803a41fd8f2c
Reviewed-on: https://chromium-review.googlesource.com/1048064
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557245}
 int GlobalConfirmInfoBar::DelegateProxy::GetButtons() const {
   return global_info_bar_ ? global_info_bar_->delegate_->GetButtons()
                           : 0;
}

 int GlobalConfirmInfoBar::DelegateProxy::GetButtons() const {
   return global_info_bar_ ? global_info_bar_->delegate_->GetButtons()
                           : 0;
}
