Re-land: base: Introduce an explicit call for reducing emulated discardable memory usage.

base/memory/discardable_memory_linux.cc

 // Copyright 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 "base/logging.h"
 #include "base/memory/discardable_memory_emulated.h"
 #include "base/memory/discardable_memory_malloc.h"
 
 namespace base {
 
 // static
-void DiscardableMemory::RegisterMemoryPressureListeners() {
-  internal::DiscardableMemoryEmulated::RegisterMemoryPressureListeners();
-}
-
-// static
-void DiscardableMemory::UnregisterMemoryPressureListeners() {
-  internal::DiscardableMemoryEmulated::UnregisterMemoryPressureListeners();
-}
-
-// static
 bool DiscardableMemory::ReduceMemoryUsage() {
   return internal::DiscardableMemoryEmulated::ReduceMemoryUsage();
 }
 
 // static
 void DiscardableMemory::GetSupportedTypes(
     std::vector<DiscardableMemoryType>* types) {
   const DiscardableMemoryType supported_types[] = {
     DISCARDABLE_MEMORY_TYPE_EMULATED,
     DISCARDABLE_MEMORY_TYPE_MALLOC
@@ skipping 30 matching lines @@
   NOTREACHED();
   return scoped_ptr<DiscardableMemory>();
 }
 
 // static
 void DiscardableMemory::PurgeForTesting() {
   internal::DiscardableMemoryEmulated::PurgeForTesting();
 }
 
 }  // namespace base