Re-land: base: Fix registering of memory pressure listeners used when emulating discardable memory.

base/memory/discardable_memory_mac.cc

 // Copyright (c) 2013 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/discardable_memory.h"
 
 #include <mach/mach.h>
 #include <sys/mman.h>
 
 #include "base/basictypes.h"
@@ skipping 71 matching lines @@
  private:
   vm_address_t buffer_;
   const size_t size_;
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryMac);
 };
 
 }  // namespace
 
 // static
+void DiscardableMemory::RegisterMemoryPressureListeners() {
+  internal::DiscardableMemoryEmulated::RegisterMemoryPressureListeners();
+}
+
+// static
+void DiscardableMemory::UnregisterMemoryPressureListeners() {
+  internal::DiscardableMemoryEmulated::UnregisterMemoryPressureListeners();
+}
+
+// static
 void DiscardableMemory::GetSupportedTypes(
     std::vector<DiscardableMemoryType>* types) {
   const DiscardableMemoryType supported_types[] = {
     DISCARDABLE_MEMORY_TYPE_MAC,
     DISCARDABLE_MEMORY_TYPE_EMULATED
   };
   types->assign(supported_types, supported_types + arraysize(supported_types));
 }
 
 // static
@@ skipping 30 matching lines @@
 }
 
 // static
 void DiscardableMemory::PurgeForTesting() {
   int state = 0;
   vm_purgable_control(mach_task_self(), 0, VM_PURGABLE_PURGE_ALL, &state);
   internal::DiscardableMemoryEmulated::PurgeForTesting();
 }
 
 }  // namespace base