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

chrome/browser/value_store/value_store_frontend.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/value_store_frontend.h"
 
+#include "chrome/browser/value_store/failing_value_store.h"
 #include "chrome/browser/value_store/leveldb_value_store.h"
 #include "content/public/browser/browser_thread.h"
 
 using content::BrowserThread;
 
 class ValueStoreFrontend::Backend : public base::RefCountedThreadSafe<Backend> {
  public:
   explicit Backend(const FilePath& db_path) : storage_(NULL) {
     BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
         base::Bind(&ValueStoreFrontend::Backend::InitOnFileThread,
@@ skipping 37 matching lines @@
       delete storage_;
     } else {
       BrowserThread::DeleteSoon(BrowserThread::FILE, FROM_HERE, storage_);
     }
   }
 
   void InitOnFileThread(const FilePath& db_path) {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
     DCHECK(!storage_);
     storage_ = LeveldbValueStore::Create(db_path);
+    if (!storage_)
+      storage_ = new FailingValueStore();

[Matt Perry, 2012/06/12 00:15:57]

This is the main difference.

I also renamed FailingSettingsStore to FailingValueStore. I must've missed that
the first time around.

   }
 
   void RunCallback(const ValueStoreFrontend::ReadCallback& callback,
                    scoped_ptr<base::Value> value) {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     callback.Run(value.Pass());
   }
 
   // The actual ValueStore that handles persisting the data to disk. Used
   // exclusively on the FILE thread.
-  LeveldbValueStore* storage_;
+  ValueStore* storage_;
 
   DISALLOW_COPY_AND_ASSIGN(Backend);
 };
 
 ValueStoreFrontend::ValueStoreFrontend(const FilePath& db_path)
     : backend_(new Backend(db_path)) {
 }
 
 ValueStoreFrontend::~ValueStoreFrontend() {
   DCHECK(CalledOnValidThread());
@@ skipping 17 matching lines @@
                  backend_, key, base::Passed(value.Pass())));
 }
 
 void ValueStoreFrontend::Remove(const std::string& key) {
   DCHECK(CalledOnValidThread());
 
   BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
       base::Bind(&ValueStoreFrontend::Backend::Remove,
                  backend_, key));
 }