Revert of Move base/prefs to components/prefs

base/prefs/pref_store_observer_mock.h

Index: base/prefs/pref_store_observer_mock.h
diff --git a/base/prefs/pref_store_observer_mock.h b/base/prefs/pref_store_observer_mock.h
index be8e4d5bc2df30bcecd5b818a5c258725a02ae5f..1b24b4e068f1be84dd3fd6e081a0c5517d97bec7 100644
--- a/base/prefs/pref_store_observer_mock.h
+++ b/base/prefs/pref_store_observer_mock.h
@@ -2,6 +2,34 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// TODO(brettw) remove this forwarding header when prefs is completely moved to
-// components.
-#include "components/prefs/pref_store_observer_mock.h"
+#ifndef BASE_PREFS_PREF_STORE_OBSERVER_MOCK_H_
+#define BASE_PREFS_PREF_STORE_OBSERVER_MOCK_H_
+
+#include <string>
+#include <vector>
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "base/prefs/pref_store.h"
+
+// A mock implementation of PrefStore::Observer.
+class PrefStoreObserverMock : public PrefStore::Observer {
+ public:
+  PrefStoreObserverMock();
+  ~PrefStoreObserverMock() override;
+
+  void VerifyAndResetChangedKey(const std::string& expected);
+
+  // PrefStore::Observer implementation
+  void OnPrefValueChanged(const std::string& key) override;
+  void OnInitializationCompleted(bool success) override;
+
+  std::vector<std::string> changed_keys;
+  bool initialized;
+  bool initialization_success;  // Only valid if |initialized|.
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PrefStoreObserverMock);
+};
+
+#endif  // BASE_PREFS_PREF_STORE_OBSERVER_MOCK_H_