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

chrome/common/origin_trials/chrome_origin_trial_policy.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 CHROME_COMMON_ORIGIN_TRIALS_CHROME_ORIGIN_TRIAL_POLICY_H_
+#define CHROME_COMMON_ORIGIN_TRIALS_CHROME_ORIGIN_TRIAL_POLICY_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/strings/string_piece.h"
+#include "content/public/common/origin_trial_policy.h"
+
+// This class is instantiated on the main/ui thread, but its methods can be
+// accessed from any thread.
+class ChromeOriginTrialPolicy : public content::OriginTrialPolicy {
+ public:
+  ChromeOriginTrialPolicy();
+  ~ChromeOriginTrialPolicy() override;
+
+  // OriginTrialPolicy interface
+  base::StringPiece GetPublicKey() const override;
+
+  bool SetPublicKeyFromASCIIString(const std::string& ascii_public_key);
+
+ private:
+  std::string public_key_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeOriginTrialPolicy);
+};
+
+#endif  // CHROME_COMMON_ORIGIN_TRIALS_CHROME_ORIGIN_TRIAL_POLICY_H_