Fetch incremental updates. Store new state in V4Store.

components/safe_browsing_db/v4_store.cc

 // Copyright 2016 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 "base/base64.h"
+#include "base/bind.h"
+#include "base/strings/stringprintf.h"
 #include "components/safe_browsing_db/v4_store.h"
 
 namespace safe_browsing {
 
+std::ostream& operator<<(std::ostream& os, const V4Store& store) {
+  os << store.DebugString();
+  return os;
+}
+
 V4Store* V4StoreFactory::CreateV4Store(
     const scoped_refptr<base::SequencedTaskRunner>& task_runner,
     const base::FilePath& store_path) {
   return new V4Store(task_runner, store_path);
 }
 
 V4Store::V4Store(const scoped_refptr<base::SequencedTaskRunner>& task_runner,
                  const base::FilePath& store_path)
-    : task_runner_(task_runner), store_path_(store_path) {}
+    : store_path_(store_path), task_runner_(task_runner) {}
 
 V4Store::~V4Store() {}
 
+std::string V4Store::DebugString() const {
+  std::string state_base64;
+  base::Base64Encode(state_, &state_base64);
+
+  return base::StringPrintf("path: %s; state: %s", store_path_.value().c_str(),
+                            state_base64.c_str());
+}
+
 bool V4Store::Reset() {
   // TODO(vakh): Implement skeleton.
+  state_ = "";
   return true;
 }
 
+void V4Store::ApplyUpdate(
+    const ListUpdateResponse& response,
+    const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
+    UpdatedStoreReadyCallback callback) {
+  std::unique_ptr<V4Store> new_store(
+      new V4Store(this->task_runner_, this->store_path_));
+
+  // TODO(vakh): The new store currently only picks up the new state. Do more.
+  new_store->state_ = response.new_client_state();
+
+  // new_store is done updating, pass it to the callback.
+  callback_task_runner->PostTask(
+      FROM_HERE, base::Bind(callback, base::Passed(&new_store)));
+}
+
 }  // namespace safe_browsing