Omnibox: Rebuild HQP Cache if it's old

chrome/browser/history/url_index_private_data.cc

Index: chrome/browser/history/url_index_private_data.cc
diff --git a/chrome/browser/history/url_index_private_data.cc b/chrome/browser/history/url_index_private_data.cc
index 8af97fa70032f2997b38002c8454be5868315374..ad389c2fcc211b8e2ac41bcf4f368496a8b93e58 100644
--- a/chrome/browser/history/url_index_private_data.cc
+++ b/chrome/browser/history/url_index_private_data.cc
@@ -444,6 +444,7 @@ scoped_refptr<URLIndexPrivateData> URLIndexPrivateData::RebuildFromHistory(
   URLDatabase::URLEnumerator history_enum;
   if (!history_db->InitURLEnumeratorForSignificant(&history_enum))
     return NULL;
+  rebuilt_data->last_time_rebuilt_from_history_ = base::Time::Now();
   for (URLRow row; history_enum.GetNextURL(&row); ) {
     rebuilt_data->IndexRow(history_db, NULL, row, languages,
                            scheme_whitelist);
@@ -475,6 +476,7 @@ void URLIndexPrivateData::CancelPendingUpdates() {
 
 scoped_refptr<URLIndexPrivateData> URLIndexPrivateData::Duplicate() const {
   scoped_refptr<URLIndexPrivateData> data_copy = new URLIndexPrivateData;
+  data_copy->last_time_rebuilt_from_history_ = last_time_rebuilt_from_history_;
   data_copy->word_list_ = word_list_;
   data_copy->available_words_ = available_words_;
   data_copy->word_map_ = word_map_;
@@ -496,6 +498,7 @@ bool URLIndexPrivateData::Empty() const {
 }
 
 void URLIndexPrivateData::Clear() {
+  last_time_rebuilt_from_history_ = base::Time();
   word_list_.clear();
   available_words_.clear();
   word_map_.clear();
@@ -908,7 +911,8 @@ bool URLIndexPrivateData::SaveToFile(const base::FilePath& file_path) {
 void URLIndexPrivateData::SavePrivateData(
     InMemoryURLIndexCacheItem* cache) const {
   DCHECK(cache);
-  cache->set_timestamp(base::Time::Now().ToInternalValue());
+  cache->set_last_rebuild_timestamp(
+      last_time_rebuilt_from_history_.ToInternalValue());
   cache->set_version(saved_cache_version_);
   // history_item_count_ is no longer used but rather than change the protobuf
   // definition use a placeholder. This will go away with the switch to SQLite.
@@ -1040,6 +1044,17 @@ void URLIndexPrivateData::SaveWordStartsMap(
 bool URLIndexPrivateData::RestorePrivateData(
     const InMemoryURLIndexCacheItem& cache,
     const std::string& languages) {
+  last_time_rebuilt_from_history_ =
+      base::Time::FromInternalValue(cache.last_rebuild_timestamp());
+  const base::TimeDelta rebuilt_ago =
+      base::Time::Now() - last_time_rebuilt_from_history_;
+  if ((rebuilt_ago > base::TimeDelta::FromDays(7)) ||
+      (rebuilt_ago < base::TimeDelta::FromDays(0))) {
+    // Cache is more than a week old or, somehow, from some time in the future.

[Peter Kasting, 2013/06/07 00:39:55]

Now() can change with system clock changes like time zone switches, DST, etc. 
We probably don't want to rebuild on every one of those.  Maybe we should allow
the database to be e.g. up to one day in the future?

[Mark P, 2013/06/07 00:50:27]

Sounds good to me.  Done.

+    // It's probably a good time to rebuild the index from history to
+    // allow synced entries to now appear, expired entries to disappear, etc.
+    return false;
+  }
   if (cache.has_version()) {
     if (cache.version() < kCurrentCacheFileVersion) {
       // Don't try to restore an old format cache file.  (This will cause