Move InfoBarResponder into its own file.

chrome/browser/infobars/infobar_responder.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/infobars/infobar_responder.h"
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "chrome/browser/infobars/infobar_service.h"
+#include "components/infobars/core/confirm_infobar_delegate.h"
+#include "components/infobars/core/infobar.h"
+
+InfoBarResponder::InfoBarResponder(InfoBarService* infobar_service,
+                                   bool should_accept)
+    : infobar_service_(infobar_service), should_accept_(should_accept) {
+  infobar_service_->AddObserver(this);
+}
+
+InfoBarResponder::~InfoBarResponder() {
+  infobar_service_->RemoveObserver(this);

[Peter Kasting, 2015/04/23 22:54:48]

Nit: Might want to comment: "This is safe even if we were already removed as an
observer in OnInfoBarAdded()."

[Michael van Ouwerkerk, 2015/04/24 11:16:38]

Done.

+}
+
+void InfoBarResponder::OnInfoBarAdded(infobars::InfoBar* infobar) {
+  infobar_service_->RemoveObserver(this);
+  ConfirmInfoBarDelegate* delegate =
+      infobar->delegate()->AsConfirmInfoBarDelegate();
+  DCHECK(delegate);
+
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(&InfoBarResponder::Respond, base::Unretained(this), delegate));
+}
+
+void InfoBarResponder::Respond(ConfirmInfoBarDelegate* delegate) {
+  if (should_accept_)
+    delegate->Accept();
+  else
+    delegate->Cancel();
+}