Remove all blimp client code.

blimp/client/core/settings/settings_observer.h

-// Copyright 2016 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 BLIMP_CLIENT_CORE_SETTINGS_SETTINGS_OBSERVER_H_
-#define BLIMP_CLIENT_CORE_SETTINGS_SETTINGS_OBSERVER_H_
-
-#include "base/observer_list.h"
-
-namespace blimp {
-namespace client {
-
-class SettingsObserver {
- public:
-  virtual ~SettingsObserver() = default;
-
-  // Invoked when enabling or disabling Blimp mode in the Settings.
-  virtual void OnBlimpModeEnabled(bool enable) {}
-
-  // Invoked when enabling or disabling to show the network stats in the
-  // Settings.
-  virtual void OnShowNetworkStatsChanged(bool enable) {}
-
-  // Invoked when enabling or disabling to download the whole document in the
-  // Settings.
-  virtual void OnRecordWholeDocumentChanged(bool enable) {}
-
-  // Invoked when a setting changed that requires the application to restart
-  // before it can take effect.
-  virtual void OnRestartRequired() {}
-
- protected:
-  SettingsObserver() = default;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(SettingsObserver);
-};
-
-}  // namespace client
-}  // namespace blimp
-
-#endif  // BLIMP_CLIENT_CORE_SETTINGS_SETTINGS_OBSERVER_H_