Unrevert r141537: Add extensions::StateStore and use that instead of

chrome/browser/value_store/caching_value_store.cc

-// 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.
-
-#include "chrome/browser/value_store/caching_value_store.h"
-
-#include "chrome/browser/value_store/leveldb_value_store.h"
-#include "content/public/browser/browser_thread.h"
-
-using content::BrowserThread;
-
-class CachingValueStore::Backend : public base::RefCountedThreadSafe<Backend> {
- public:
-  typedef base::Callback<void(scoped_ptr<base::DictionaryValue>)> ReadyCallback;
-  Backend() : storage_(NULL) {}
-
-  void Init(const FilePath& db_path, ReadyCallback callback) {
-    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-        base::Bind(&CachingValueStore::Backend::InitOnFileThread,
-                   this, db_path, callback));
-  }
-
-  void Set(const std::string& key, scoped_ptr<base::Value> value) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-    // We've already checked that the value has changed, so don't bother
-    // checking again. Also, skip changes to avoid wasted copies.
-    storage_->Set(ValueStore::IGNORE_QUOTA |
-                      ValueStore::NO_GENERATE_CHANGES |
-                      ValueStore::NO_CHECK_OLD_VALUE,
-                  key, *value.get());
-  }
-
-  void Remove(const std::string& key) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-    storage_->Remove(key);
-  }
-
- private:
-  friend class base::RefCountedThreadSafe<Backend>;
-
-  virtual ~Backend() {
-    if (BrowserThread::CurrentlyOn(BrowserThread::FILE)) {
-      delete storage_;
-    } else {
-      BrowserThread::DeleteSoon(BrowserThread::FILE, FROM_HERE, storage_);
-    }
-  }
-
-  void InitOnFileThread(const FilePath& db_path, ReadyCallback callback) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-    DCHECK(!storage_);
-    storage_ = LeveldbValueStore::Create(db_path);
-
-    ValueStore::ReadResult result = storage_->Get();
-    if (result->HasError()) {
-      callback.Run(scoped_ptr<base::DictionaryValue>(NULL));
-    } else {
-      callback.Run(result->settings().Pass());
-    }
-  }
-
-  // The actual ValueStore that handles persisting the data to disk. Used
-  // exclusively on the FILE thread.
-  LeveldbValueStore* storage_;
-
-  DISALLOW_COPY_AND_ASSIGN(Backend);
-};
-
-CachingValueStore::CachingValueStore(const FilePath& db_path)
-    : backend_(new Backend()) {
-  backend_->Init(db_path,
-                 base::Bind(&CachingValueStore::OnBackendReady, AsWeakPtr()));
-}
-
-CachingValueStore::~CachingValueStore() {
-}
-
-bool CachingValueStore::Get(const std::string& key,
-                            const base::Value** result) {
-  DCHECK(CalledOnValidThread());
-  DCHECK(IsInitialized());
-
-  base::Value* value = NULL;
-  if (cache_->GetWithoutPathExpansion(key, &value)) {
-    *result = value;
-    return true;
-  }
-  return false;
-}
-
-void CachingValueStore::Set(const std::string& key, base::Value* value) {
-  DCHECK(CalledOnValidThread());
-  DCHECK(IsInitialized());
-
-  scoped_ptr<base::Value> new_value(value);
-  base::Value* old_value = NULL;
-  if (!cache_->GetWithoutPathExpansion(key, &old_value) ||
-      !value->Equals(old_value)) {
-    cache_->SetWithoutPathExpansion(key, new_value.release());
-
-    scoped_ptr<base::Value> passed_value(value->DeepCopy());
-    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-        base::Bind(&CachingValueStore::Backend::Set,
-                   backend_, key, base::Passed(passed_value.Pass())));
-  }
-}
-
-void CachingValueStore::Remove(const std::string& key) {
-  DCHECK(CalledOnValidThread());
-  DCHECK(IsInitialized());
-
-  if (cache_->RemoveWithoutPathExpansion(key, NULL)) {
-    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-        base::Bind(&CachingValueStore::Backend::Remove,
-                   backend_, key));
-  }
-}
-
-bool CachingValueStore::IsInitialized() {
-  DCHECK(CalledOnValidThread());
-  return !!cache_.get();
-}
-
-void CachingValueStore::AddObserver(Observer* observer) {
-  DCHECK(CalledOnValidThread());
-  observers_.AddObserver(observer);
-}
-
-void CachingValueStore::RemoveObserver(Observer* observer) {
-  DCHECK(CalledOnValidThread());
-  observers_.RemoveObserver(observer);
-}
-
-void CachingValueStore::OnBackendReady(
-    scoped_ptr<base::DictionaryValue> values) {
-  DCHECK(CalledOnValidThread());
-  DCHECK(!cache_.get());
-  cache_.swap(values);
-
-  FOR_EACH_OBSERVER(Observer, observers_, OnInitializationComplete());
-}