memory coordinator: Add MemoryCoordinatorClient::OnPurgeMemory()

base/memory/memory_coordinator_client_registry.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 "base/memory/memory_coordinator_client_registry.h"
 
 namespace base {
 
 // static
 MemoryCoordinatorClientRegistry*
@@ skipping 16 matching lines @@
 void MemoryCoordinatorClientRegistry::Unregister(
     MemoryCoordinatorClient* client) {
   clients_->RemoveObserver(client);
 }
 
 void MemoryCoordinatorClientRegistry::Notify(MemoryState state) {
   clients_->Notify(FROM_HERE,
                    &base::MemoryCoordinatorClient::OnMemoryStateChange, state);
 }
 
+void MemoryCoordinatorClientRegistry::PurgeMemory() {
+  clients_->Notify(FROM_HERE, &base::MemoryCoordinatorClient::OnPurgeMemory);
+}
+
 }  // namespace base