Add foundation for trimming the AffiliationDatabase.

components/password_manager/core/browser/affiliation_backend.cc

 // Copyright 2015 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/password_manager/core/browser/affiliation_backend.h"
 
 #include <stdint.h>
+#include <algorithm>
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/clock.h"
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "components/password_manager/core/browser/affiliation_database.h"
@@ skipping 73 matching lines @@
     return;
   facet_manager->CancelPrefetch(keep_fresh_until);
 
   if (facet_manager->CanBeDiscarded())
     facet_managers_.erase(facet_uri);
 }
 
 void AffiliationBackend::TrimCache() {
   DCHECK(thread_checker_ && thread_checker_->CalledOnValidThread());
 
-  // TODO(engedy): Implement this. crbug.com/437865.
-  NOTIMPLEMENTED();
+  // Discard all equivalence classes except those that contain >= 1 facet for
+  // which there is a FacetManager claiming that it needs to keep the data.
+  std::vector<AffiliatedFacetsWithUpdateTime> all_affiliations;
+  cache_->GetAllAffiliations(&all_affiliations);
+  for (const auto& affiliation : all_affiliations) {
+    bool can_discard = true;
+    for (const auto& facet_uri : affiliation.facets) {
+      FacetManager* facet_manager = facet_managers_.get(facet_uri);
+      if (facet_manager && !facet_manager->CanCachedDataBeDiscarded()) {
+        can_discard = false;
+        break;
+      }
+    }
+    if (can_discard) {
+      // The database should not be serving empty equivalence classes.
+      CHECK(affiliation.facets.size());
+      cache_->DeleteAffiliationsForFacet(affiliation.facets[0]);
+    }
+  }
+}
+
+// static
+void AffiliationBackend::DeleteCache(const base::FilePath& db_path) {
+  AffiliationDatabase::Delete(db_path);
 }
 
 FacetManager* AffiliationBackend::GetOrCreateFacetManager(
     const FacetURI& facet_uri) {
   if (!facet_managers_.contains(facet_uri)) {
     scoped_ptr<FacetManager> new_manager(
         new FacetManager(facet_uri, this, clock_.get()));
     facet_managers_.add(facet_uri, new_manager.Pass());
   }
   return facet_managers_.get(facet_uri);
@@ skipping 135 matching lines @@
   }
   last_request_time_ = clock_->Now();
 }
 
 void AffiliationBackend::SetThrottlerForTesting(
     scoped_ptr<AffiliationFetchThrottler> throttler) {
   throttler_ = throttler.Pass();
 }
 
 }  // namespace password_manager