Purge browser cache for dom storage in a smarter way

content/browser/dom_storage/dom_storage_context_impl.cc

 // Copyright (c) 2012 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 "content/browser/dom_storage/dom_storage_context_impl.h"
 
 #include <stddef.h>
 #include <stdlib.h>
 
 #include "base/bind.h"
@@ skipping 378 matching lines @@
 
 void DOMStorageContextImpl::StartScavengingUnusedSessionStorage() {
   if (session_storage_database_.get()) {
     task_runner_->PostDelayedTask(
         FROM_HERE, base::Bind(&DOMStorageContextImpl::FindUnusedNamespaces,
                               this),
         base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
   }
 }
 
+void DOMStorageContextImpl::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  if (is_shutdown_)
+    return;
+
+  DOMStorageNamespace::PurgeOption option = DOMStorageNamespace::PURGE_UNOPENED;
+  if (memory_pressure_level ==
+      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL)
+    option = DOMStorageNamespace::PURGE_AGGRESSIVE;
+  for (const auto& it : namespaces_)
+    it.second->PurgeMemory(option);
+}
+
 bool DOMStorageContextImpl::OnMemoryDump(
     const base::trace_event::MemoryDumpArgs& args,
     base::trace_event::ProcessMemoryDump* pmd) {
   for (const auto& it : namespaces_) {
     it.second->OnMemoryDump(pmd);
   }
   if (session_storage_database_)
     session_storage_database_->OnMemoryDump(pmd);
   return true;
 }
@@ skipping 61 matching lines @@
   if (!deletable_persistent_namespace_ids_.empty()) {
     task_runner_->PostDelayedTask(
         FROM_HERE, base::Bind(
             &DOMStorageContextImpl::DeleteNextUnusedNamespace,
             this),
         base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
   }
 }
 
 }  // namespace content