Clear SSLClientSessionCache on low memory notifications.

net/ssl/ssl_client_session_cache.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 "net/ssl/ssl_client_session_cache.h"
 
 #include <utility>
 
 #include "base/time/clock.h"
 #include "base/time/default_clock.h"
 
 namespace net {
 
 SSLClientSessionCache::SSLClientSessionCache(const Config& config)
     : clock_(new base::DefaultClock),
       config_(config),
       cache_(config.max_entries),
-      lookups_since_flush_(0) {}
+      lookups_since_flush_(0) {
+  memory_pressure_listener_.reset(new base::MemoryPressureListener(base::Bind(
+      &SSLClientSessionCache::OnMemoryPressure, base::Unretained(this))));
+}
 
 SSLClientSessionCache::~SSLClientSessionCache() {
   Flush();
 }
 
 size_t SSLClientSessionCache::size() const {
   return cache_.size();
 }
 
 ScopedSSL_SESSION SSLClientSessionCache::Lookup(const std::string& cache_key) {
@@ skipping 55 matching lines @@
   CacheEntryMap::iterator iter = cache_.begin();
   while (iter != cache_.end()) {
     if (IsExpired(iter->second.get(), now)) {
       iter = cache_.Erase(iter);
     } else {
       ++iter;
     }
   }
 }
 
+void SSLClientSessionCache::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  switch (memory_pressure_level) {
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:
+      break;
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
+      FlushExpiredSessions();
+      break;
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
+      Flush();
+      break;
+  }
+}
+
 }  // namespace net