Refactor OriginTrialPolicy to be an abstract interface in content/public/common

chrome/common/origin_trials/origin_trial_key_manager.h

-// Copyright (c) 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 CHROME_COMMON_ORIGIN_TRIALS_ORIGIN_TRIAL_KEY_MANAGER_H_
-#define CHROME_COMMON_ORIGIN_TRIALS_ORIGIN_TRIAL_KEY_MANAGER_H_
-
-#include <set>
-#include <string>
-
-#include "base/macros.h"
-#include "base/strings/string_piece.h"
-
-// This class is instantiated on the main/ui thread, but its methods can be
-// accessed from any thread.
-class OriginTrialKeyManager {
- public:
-  OriginTrialKeyManager();
-  ~OriginTrialKeyManager();
-
-  bool SetPublicKeyFromASCIIString(const std::string& ascii_public_key);
-  base::StringPiece GetPublicKey() const;
-  bool SetDisabledFeatures(const std::string& disabled_feature_list);
-  bool IsFeatureDisabled(base::StringPiece feature) const;
-
- private:
-  std::string public_key_;
-  std::set<std::string> disabled_features_;
-
-  DISALLOW_COPY_AND_ASSIGN(OriginTrialKeyManager);
-};
-
-#endif  // CHROME_COMMON_ORIGIN_TRIALS_ORIGIN_TRIAL_KEY_MANAGER_H_