Support multiple PrefStores

Add interface for multi_pref_store_manager.

BUG=40259
TEST=Unittests in pref_service_unittest.cc, pref_value_store_unittest.cc

Review URL: http://codereview.chromium.org/1957005
Patch from Markus Heintz <markusheintz@google.com>.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@49048 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 91 insertions, 0 deletions

diff --git a/chrome/browser/pref_value_store.h b/chrome/browser/pref_value_store.h
new file mode 100644
index 0000000..a3d92d5
--- /dev/null
+++ b/chrome/browser/pref_value_store.h
@@ -0,0 +1,91 @@
+// Copyright (c) 2010 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_BROWSER_PREF_VALUE_STORE_H_
+#define CHROME_BROWSER_PREF_VALUE_STORE_H_
+
+#include "base/basictypes.h"
+#include "base/file_path.h"
+#include "base/string16.h"
+#include "base/scoped_ptr.h"
+#include "base/values.h"
+#include "chrome/common/pref_store.h"
+
+class PrefStore;
+
+// The class PrefValueStore provides values for preferences. Each Preference
+// has a unique name. This name is used to retrieve the value of a Preference.
+// The value of a preference can be either managed, user-defined or recommended.
+// Managed preference values are set (managed) by a third person (like an
+// admin for example). They have the highest priority and can not be
+// altered by the user.
+// User-defined values are chosen by the user. If there is already
+// a managed value for a preference the user-defined value is ignored and
+// the managed value is used (returned).
+// Otherwise user-defined values have a higher precedence than recommended
+// values. Recommended preference values are set by a third person
+// (like an admin).
+class PrefValueStore {
+ public:
+  // |managed_prefs| contains all managed preference values. They have the
+  // highest priority and precede user-defined preference values. |user_prefs|
+  // contains all user-defined preference values. User-defined values precede
+  // recommended values. |recommended_prefs| contains all recommended
+  // preference values.
+  PrefValueStore(PrefStore* managed_prefs,
+                 PrefStore* user_prefs,
+                 PrefStore* recommended_prefs);
+
+  ~PrefValueStore();
+
+  // Get the preference value for the given preference name.
+  // Return true if a value for the given preference name was found.
+  bool GetValue(const std::wstring& name, Value** out_value) const;
+
+  // Read preference values into the three PrefStores so that they are available
+  // through the GetValue method.
+  PrefStore::PrefReadError ReadPrefs();
+
+  // Write user settable preference values. Return true if writing values was
+  // successfull.
+  bool WritePrefs();
+
+  // Calls the method ScheduleWritePrefs on the PrefStores.
+  void ScheduleWritePrefs();
+
+  // Returns true if the PrefValueStore contains the given preference.
+  bool HasPrefPath(const wchar_t* name) const;
+
+  // Returns true if the PrefValueStore is read-only.
+  // Because the managed and recommended PrefStores are always read-only, the
+  // PrefValueStore as a whole is read-only if the PrefStore containing the user
+  // preferences is read-only.
+  bool ReadOnly();
+
+  // Alters the user-defined value of a preference. Even if the preference is
+  // managed this method allows the user-defined value of the preference to be
+  // set. But GetValue calls will not return this value as long as the
+  // preference is managed. Instead GetValue will return the managed value
+  // of the preference. Note that the PrefValueStore takes the ownership of
+  // the value referenced by |in_value|.
+  void SetUserPrefValue(const wchar_t* name, Value* in_value);
+
+  // Removes a value from the PrefValueStore. If a preference is managed
+  // or recommended this function should have no effect.
+  void RemoveUserPrefValue(const wchar_t* name);
+
+  // Returns true if the preference with the given name is managed.
+  // A preference is managed if a managed value is available for that
+  // preference.
+  bool PrefValueIsManaged(const wchar_t* name);
+
+ private:
+  scoped_ptr<PrefStore> managed_prefs_;
+  scoped_ptr<PrefStore> user_prefs_;
+  scoped_ptr<PrefStore> recommended_prefs_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefValueStore);
+};
+
+#endif  // CHROME_BROWSER_PREF_VALUE_STORE_H_