Adding a SQL implementation of the backing store for previews opt outs

components/previews/core/previews_black_list.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 "components/previews/core/previews_black_list.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/optional.h"
 #include "base/time/clock.h"
 #include "base/time/time.h"
 #include "components/previews/core/previews_black_list_item.h"
 #include "components/previews/core/previews_experiments.h"
 #include "url/gurl.h"
 
 namespace previews {
 
 PreviewsBlackList::PreviewsBlackList(
     std::unique_ptr<PreviewsOptOutStore> opt_out_store,
     std::unique_ptr<base::Clock> clock)
     : loaded_(false),
       opt_out_store_(std::move(opt_out_store)),
       clock_(std::move(clock)),
-      weak_factory_(this) {
+      weak_factory_(this) {}
+
+PreviewsBlackList::~PreviewsBlackList() {}
+
+void PreviewsBlackList::Initialize() {

[tbansal1, 2016/10/04 15:01:21]

Add thread checker.

[RyanSturm, 2016/10/04 19:10:23]

I'm undoing this. It doesn't actually help anything.

   if (opt_out_store_) {
     opt_out_store_->LoadBlackList(base::Bind(
         &PreviewsBlackList::LoadBlackListDone, weak_factory_.GetWeakPtr()));
   } else {
     LoadBlackListDone(base::MakeUnique<BlackListItemMap>());
   }
 }
 
-PreviewsBlackList::~PreviewsBlackList() {}
-
 void PreviewsBlackList::AddPreviewNavigation(const GURL& url,
                                              bool opt_out,
                                              PreviewsType type) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(url.has_host());
   // If the |black_list_item_map_| has been loaded from |opt_out_store_|,
   // synchronous operations will be accurate. Otherwise, queue the task to run
   // asynchronously.
   if (loaded_) {
     AddPreviewNavigationSync(url, opt_out, type);
@@ skipping 96 matching lines @@
     }
     if (iter->second->most_recent_opt_out_time().value() < oldest_opt_out) {
       oldest_opt_out = iter->second->most_recent_opt_out_time().value();
       item_to_delete = iter;
     }
   }
   black_list_item_map_->erase(item_to_delete);
 }
 
 }  // namespace previews