Remove JsonPrefStore pruning of empty values on write.

android_webview/browser/aw_pref_store.h

 // Copyright (c) 2013 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 ANDROID_WEBVIEW_BROWSER_AW_PREF_STORE_H_
 #define ANDROID_WEBVIEW_BROWSER_AW_PREF_STORE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 19 matching lines @@
   virtual bool IsInitializationComplete() const OVERRIDE;
 
   // PersistentPrefStore overrides:
   virtual bool GetMutableValue(const std::string& key,
                                base::Value** result) OVERRIDE;
   virtual void ReportValueChanged(const std::string& key) OVERRIDE;
   virtual void SetValue(const std::string& key, base::Value* value) OVERRIDE;
   virtual void SetValueSilently(const std::string& key,
                                 base::Value* value) OVERRIDE;
   virtual void RemoveValue(const std::string& key) OVERRIDE;
-  virtual void MarkNeedsEmptyValue(const std::string& key) OVERRIDE;
   virtual bool ReadOnly() const OVERRIDE;
   virtual PrefReadError GetReadError() const OVERRIDE;
   virtual PersistentPrefStore::PrefReadError ReadPrefs() OVERRIDE;
   virtual void ReadPrefsAsync(ReadErrorDelegate* error_delegate) OVERRIDE;
   virtual void CommitPendingWrite() OVERRIDE {}
 
  protected:
   virtual ~AwPrefStore();
 
  private:
   // Stores the preference values.
   PrefValueMap prefs_;
 
   ObserverList<PrefStore::Observer, true> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(AwPrefStore);
 };
 
 #endif  // ANDROID_WEBVIEW_BROWSER_AW_PREF_STORE_H_