Adding a short blacklist period after every previews opt out

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"

[tbansal1, 2016/10/25 00:47:41]

Remove this include.

[RyanSturm, 2016/10/25 17:15:38]

Done.

 #include "components/previews/core/previews_black_list_item.h"
 #include "components/previews/core/previews_experiments.h"
 #include "url/gurl.h"
 
 namespace previews {
 
 namespace {
 
 void EvictOldestOptOut(BlackListItemMap* black_list_item_map) {
   // TODO(ryansturm): Add UMA. crbug.com/647717
@@ skipping 33 matching lines @@
   }
 }
 
 PreviewsBlackList::~PreviewsBlackList() {}
 
 void PreviewsBlackList::AddPreviewNavigation(const GURL& url,
                                              bool opt_out,
                                              PreviewsType type) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(url.has_host());
+  if (opt_out) {
+    last_opt_out_time_ = clock_->Now();
+  }
   // 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);
   } else {
     QueuePendingTask(base::Bind(&PreviewsBlackList::AddPreviewNavigationSync,
                                 base::Unretained(this), url, opt_out, type));
   }
 }
 
 void PreviewsBlackList::AddPreviewNavigationSync(const GURL& url,
                                                  bool opt_out,
                                                  PreviewsType type) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(url.has_host());
   DCHECK(loaded_);
   std::string host_name = url.host();
   base::Time now = clock_->Now();
   PreviewsBlackListItem* item =
       GetOrCreateBlackListItem(black_list_item_map_.get(), host_name);
   item->AddPreviewNavigation(opt_out, now);
   DCHECK_LE(black_list_item_map_->size(),
             params::MaxInMemoryHostsInBlackList());
   if (!opt_out_store_)
     return;
   opt_out_store_->AddPreviewNavigation(opt_out, host_name, type, now);
 }
 
 bool PreviewsBlackList::IsLoadedAndAllowed(const GURL& url,

[tbansal1, 2016/10/25 00:47:41]

At some point in future, it might be useful for this function to return an enum
describing why the preview can;t be shown. Consumers can than use it to record
UMA (which can help them in understanding how to tune different field trial
params).

[RyanSturm, 2016/10/25 17:15:38]

Agreed. Seperate CL when someone wants it. We'd need to "correctly" order them
here and in the method that calls this.

                                            PreviewsType type) const {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(url.has_host());
   if (!loaded_)
     return false;
+  if (last_opt_out_time_ &&
+      clock_->Now() <
+          last_opt_out_time_.value() + params::SingleOptOutDuration()) {
+    return false;
+  }
   PreviewsBlackListItem* black_list_item =
       GetBlackListItem(*black_list_item_map_, url.host());
   return !black_list_item || !black_list_item->IsBlackListed(clock_->Now());
 }
 
 void PreviewsBlackList::ClearBlackList(base::Time begin_time,
                                        base::Time end_time) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_LE(begin_time, end_time);
   // If the |black_list_item_map_| has been loaded from |opt_out_store_|,
@@ skipping 68 matching lines @@
   DCHECK_LT(black_list_item_map->size(), params::MaxInMemoryHostsInBlackList());
   black_list_item = new PreviewsBlackListItem(
       params::MaxStoredHistoryLengthForBlackList(),
       params::BlackListOptOutThreshold(), params::BlackListDuration());
   black_list_item_map->operator[](host_name) =
       base::WrapUnique(black_list_item);
   return black_list_item;
 }
 
 }  // namespace previews