Sanitize PrefStore interface.

This reworks the PrefStore interface, specifically:

- Split up the interface into PrefStore, which only provides reading functionality, and the derived PersistentPrefStore for the actual user pref store
- Remove the hurt-me-plenty prefs() function from PrefStore, instead provide Get/Set/Remove operations
- Remove special handling of default and user pref store from PrefValueStore and put it into PrefService
- Pref change notification handling now almost exclusively handled through PrefValueStore
- Adjust all consumers of these interfaces (but keep ConfigurationPolicyPrefStore untouched, that's up next on the list)

BUG=64232
TEST=existing unit tests

Review URL: http://codereview.chromium.org/5646003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@68736 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 69 insertions, 0 deletions

diff --git a/chrome/common/persistent_pref_store.h b/chrome/common/persistent_pref_store.h
new file mode 100644
index 0000000..9e2fb0a
--- /dev/null
+++ b/chrome/common/persistent_pref_store.h
@@ -0,0 +1,69 @@
+// 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_COMMON_PERSISTENT_PREF_STORE_H_
+#define CHROME_COMMON_PERSISTENT_PREF_STORE_H_
+#pragma once
+
+#include <string>
+
+#include <chrome/common/pref_store.h>
+
+// This interface is complementary to the PrefStore interface, declaring
+// additional functionatliy that adds support for setting values and persisting
+// the data to some backing store.
+class PersistentPrefStore : public PrefStore {
+ public:
+  virtual ~PersistentPrefStore() {}
+
+  // Unique integer code for each type of error so we can report them
+  // distinctly in a histogram.
+  // NOTE: Don't change the order here as it will change the server's meaning
+  // of the histogram.
+  enum PrefReadError {
+    PREF_READ_ERROR_NONE = 0,
+    PREF_READ_ERROR_JSON_PARSE,
+    PREF_READ_ERROR_JSON_TYPE,
+    PREF_READ_ERROR_ACCESS_DENIED,
+    PREF_READ_ERROR_FILE_OTHER,
+    PREF_READ_ERROR_FILE_LOCKED,
+    PREF_READ_ERROR_NO_FILE,
+    PREF_READ_ERROR_JSON_REPEAT,
+    PREF_READ_ERROR_OTHER,
+    PREF_READ_ERROR_FILE_NOT_SPECIFIED
+  };
+
+  // Sets a |value| for |key| in the store. Assumes ownership of |value|, which
+  // must be non-NULL.
+  virtual void SetValue(const std::string& key, Value* value) = 0;
+
+  // Same as SetValue, but doesn't generate notifications. This is used by
+  // GetMutableDictionary() and GetMutableList() in order to put empty entries
+  // into the user pref store. Using SetValue is not an option since existing
+  // tests rely on the number of notifications generated.
+  //
+  // TODO(mnissler, danno): Can we replace GetMutableDictionary() and
+  // GetMutableList() with something along the lines of ScopedPrefUpdate that
+  // updates the value in the end?
+  virtual void SetValueSilently(const std::string& key, Value* value) = 0;
+
+  // Removes the value for |key|.
+  virtual void RemoveValue(const std::string& key) = 0;
+
+  // Whether the store is in a pseudo-read-only mode where changes are not
+  // actually persisted to disk.  This happens in some cases when there are
+  // read errors during startup.
+  virtual bool ReadOnly() const = 0;
+
+  // Reads the preferences from disk.
+  virtual PrefReadError ReadPrefs() = 0;
+
+  // Writes the preferences to disk immediately.
+  virtual bool WritePrefs() = 0;
+
+  // Schedules an asynchronous write operation.
+  virtual void ScheduleWritePrefs() = 0;
+};
+
+#endif  // CHROME_COMMON_PERSISTENT_PREF_STORE_H_