Move InfoBarResponder into its own file.

chrome/browser/infobars/infobar_responder.h

Index: chrome/browser/infobars/infobar_responder.h
diff --git a/chrome/browser/infobars/infobar_responder.h b/chrome/browser/infobars/infobar_responder.h
new file mode 100644
index 0000000000000000000000000000000000000000..eb481dd99fb97e0f2a923bd49be01f4bf32fbc46
--- /dev/null
+++ b/chrome/browser/infobars/infobar_responder.h
@@ -0,0 +1,36 @@
+// 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.
+
+#ifndef CHROME_BROWSER_INFOBARS_INFOBAR_RESPONDER_H_
+#define CHROME_BROWSER_INFOBARS_INFOBAR_RESPONDER_H_
+
+#include "components/infobars/core/infobar_manager.h"
+
+namespace infobars {
+class InfoBar;
+}
+
+class ConfirmInfoBarDelegate;
+class InfoBarService;
+
+// Accepts or rejects the first shown confirm infobar. The infobar will be
+// handled asynchronously, to imitate the behavior of a real person. For use in
+// tests.

[Peter Kasting, 2015/04/23 00:14:08]

Nit: How about:

Used by test code to asynchronously respond to the first infobar shown, which
must have a ConfirmInfoBarDelegate.  This can be used to ensure various
interaction flows work correctly.

The asynchronous response matches how real users will use the infobar.

[Michael van Ouwerkerk, 2015/04/23 13:36:09]

Done.

+class InfoBarResponder : public infobars::InfoBarManager::Observer {
+ public:
+  InfoBarResponder(InfoBarService* infobar_service, bool accept);

[Peter Kasting, 2015/04/23 00:14:08]

Nit: Change name to |should_accept| (also the member variable) and add comment:

If |should_accept| is true, the responder will asynchronously Accept() the
infobar; otherwise it will Cancel() it.

[Michael van Ouwerkerk, 2015/04/23 13:36:09]

Done.

+  ~InfoBarResponder() override;
+
+  // infobars::InfoBarManager::Observer

[Peter Kasting, 2015/04/23 00:14:08]

Nit: Add trailing colon

[Michael van Ouwerkerk, 2015/04/23 13:36:09]

Done.

+  void OnInfoBarAdded(infobars::InfoBar* infobar) override;
+
+ private:
+  void Respond(ConfirmInfoBarDelegate* delegate);
+
+  InfoBarService* infobar_service_;
+  bool accept_;
+  bool has_observed_;

[Peter Kasting, 2015/04/23 00:14:08]

Nit: |infobar_seen_| might be slightly more descriptive

[Michael van Ouwerkerk, 2015/04/23 13:36:10]

No longer needed.

+};

[Peter Kasting, 2015/04/23 00:14:08]

Nit: DISALLOW_COPY_AND_ASSIGN

[Michael van Ouwerkerk, 2015/04/23 13:36:10]

Done.

+
+#endif  // CHROME_BROWSER_INFOBARS_INFOBAR_RESPONDER_H_