Update from https://crrev.com/327068

base/test/mock_entropy_provider.h

+// 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 BASE_TEST_MOCK_ENTROPY_PROVIDER_H_
+#define BASE_TEST_MOCK_ENTROPY_PROVIDER_H_
+
+#include "base/metrics/field_trial.h"
+
+namespace base {
+
+class MockEntropyProvider : public base::FieldTrial::EntropyProvider {
+ public:
+  ~MockEntropyProvider() override;
+
+  // base::FieldTrial::EntropyProvider:
+  double GetEntropyForTrial(const std::string& trial_name,
+                            uint32 randomization_seed) const override;
+};
+
+}  // namespace base
+
+#endif  // BASE_TEST_MOCK_ENTROPY_PROVIDER_H_