Update from https://crrev.com/316786

base/memory/discardable_memory_emulated.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_emulated.h"
 
 #include "base/lazy_instance.h"
 #include "base/memory/discardable_memory_manager.h"
 
 namespace base {
@@ skipping 50 matching lines @@
 bool DiscardableMemoryEmulated::ReduceMemoryUsage() {
   return g_manager.Pointer()->ReduceMemoryUsage();
 }
 
 // static
 void DiscardableMemoryEmulated::ReduceMemoryUsageUntilWithinLimit(
     size_t bytes) {
   g_manager.Pointer()->ReduceMemoryUsageUntilWithinLimit(bytes);
 }
 
-// static
-void DiscardableMemoryEmulated::PurgeForTesting() {
-  g_manager.Pointer()->PurgeAll();
-}
-
 bool DiscardableMemoryEmulated::Initialize() {
   return Lock() != DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
 }
 
 DiscardableMemoryLockStatus DiscardableMemoryEmulated::Lock() {
   DCHECK(!is_locked_);
 
   bool purged = false;
   if (!g_manager.Pointer()->AcquireLock(this, &purged))
     return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
@@ skipping 20 matching lines @@
     return true;
 
   memory_.reset(new uint8[bytes_]);
   return false;
 }
 
 void DiscardableMemoryEmulated::Purge() {
   memory_.reset();
 }
 
-bool DiscardableMemoryEmulated::IsMemoryResident() const {
-  return true;
-}
-
 }  // namespace internal
 }  // namespace base