Implement lossy pref behavior for JsonPrefStore.

base/prefs/json_pref_store.h

 // Copyright (c) 2012 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_PREFS_JSON_PREF_STORE_H_
 #define BASE_PREFS_JSON_PREF_STORE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 54 matching lines @@
   // |pref_alternate_filename| is the path to an alternate file which the
   // desired prefs may have previously been written to. If |pref_filename|
   // doesn't exist and |pref_alternate_filename| does, |pref_alternate_filename|
   // will be moved to |pref_filename| before the read occurs.
   JsonPrefStore(
       const base::FilePath& pref_filename,
       const base::FilePath& pref_alternate_filename,
       const scoped_refptr<base::SequencedTaskRunner>& sequenced_task_runner,
       scoped_ptr<PrefFilter> pref_filter);
 
+  // Constructor for testing which allows an ImportantFileWriter to be
+  // specified.
+  JsonPrefStore(
+      const base::FilePath& pref_filename,
+      const base::FilePath& pref_alternate_filename,
+      const scoped_refptr<base::SequencedTaskRunner>& sequenced_task_runner,
+      scoped_ptr<base::ImportantFileWriter> file_writer,
+      scoped_ptr<PrefFilter> pref_filter);
+
   // PrefStore overrides:
   bool GetValue(const std::string& key,
                 const base::Value** result) const override;
   void AddObserver(PrefStore::Observer* observer) override;
   void RemoveObserver(PrefStore::Observer* observer) override;
   bool HasObservers() const override;
   bool IsInitializationComplete() const override;
 
   // PersistentPrefStore overrides:
   bool GetMutableValue(const std::string& key, base::Value** result) override;
@@ skipping 98 matching lines @@
   // potentially been intercepted and modified by |pref_filter_|.
   // |initialization_successful| is pre-determined by OnFileRead() and should
   // be used when reporting OnInitializationCompleted().
   // |schedule_write| indicates whether a write should be immediately scheduled
   // (typically because the |pref_filter_| has already altered the |prefs|) --
   // this will be ignored if this store is read-only.
   void FinalizeFileRead(bool initialization_successful,
                         scoped_ptr<base::DictionaryValue> prefs,
                         bool schedule_write);
 
+  // Schedule a write with the file writer as long as |flags| doesn't contain
+  // WriteablePrefStore::LOSSY_PREF_WRITE_FLAG.
+  void ScheduleWrite(uint32 flags);
+
   const base::FilePath path_;
   const base::FilePath alternate_path_;
   const scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;
 
   scoped_ptr<base::DictionaryValue> prefs_;
 
   bool read_only_;
 
   // Helper for safely writing pref data.
-  base::ImportantFileWriter writer_;
+  scoped_ptr<base::ImportantFileWriter> writer_;
 
   scoped_ptr<PrefFilter> pref_filter_;
   ObserverList<PrefStore::Observer, true> observers_;
 
   scoped_ptr<ReadErrorDelegate> error_delegate_;
 
   bool initialized_;
   bool filtering_in_progress_;
+  bool pending_lossy_write_;
   PrefReadError read_error_;
 
   std::set<std::string> keys_need_empty_value_;
 
   WriteCountHistogram write_count_histogram_;
 
   DISALLOW_COPY_AND_ASSIGN(JsonPrefStore);
 };
 
 #endif  // BASE_PREFS_JSON_PREF_STORE_H_