Update from https://crrev.com/320343

base/memory/discardable_memory_emulated.cc

Index: base/memory/discardable_memory_emulated.cc
diff --git a/base/memory/discardable_memory_emulated.cc b/base/memory/discardable_memory_emulated.cc
deleted file mode 100644
index b12d7ce0eadbc5648a2a5e1aab0484a3dce6577f..0000000000000000000000000000000000000000
--- a/base/memory/discardable_memory_emulated.cc
+++ /dev/null
@@ -1,112 +0,0 @@
-// 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 {
-namespace {
-
-// This is admittedly pretty magical.
-const size_t kEmulatedMemoryLimit = 512 * 1024 * 1024;
-const size_t kEmulatedSoftMemoryLimit = 32 * 1024 * 1024;
-const size_t kEmulatedHardMemoryLimitExpirationTimeMs = 1000;
-
-// internal::DiscardableMemoryManager has an explicit constructor that takes
-// a number of memory limit parameters. The LeakyLazyInstanceTraits doesn't
-// handle the case. Thus, we need our own class here.
-struct DiscardableMemoryManagerLazyInstanceTraits {
-  // Leaky as discardable memory clients can use this after the exit handler
-  // has been called.
-  static const bool kRegisterOnExit = false;
-#ifndef NDEBUG
-  static const bool kAllowedToAccessOnNonjoinableThread = true;
-#endif
-
-  static internal::DiscardableMemoryManager* New(void* instance) {
-    return new (instance) internal::DiscardableMemoryManager(
-        kEmulatedMemoryLimit,
-        kEmulatedSoftMemoryLimit,
-        TimeDelta::FromMilliseconds(kEmulatedHardMemoryLimitExpirationTimeMs));
-  }
-  static void Delete(internal::DiscardableMemoryManager* instance) {
-    instance->~DiscardableMemoryManager();
-  }
-};
-
-LazyInstance<internal::DiscardableMemoryManager,
-             DiscardableMemoryManagerLazyInstanceTraits>
-    g_manager = LAZY_INSTANCE_INITIALIZER;
-
-}  // namespace
-
-namespace internal {
-
-DiscardableMemoryEmulated::DiscardableMemoryEmulated(size_t bytes)
-    : bytes_(bytes),
-      is_locked_(false) {
-  g_manager.Pointer()->Register(this, bytes);
-}
-
-DiscardableMemoryEmulated::~DiscardableMemoryEmulated() {
-  if (is_locked_)
-    Unlock();
-  g_manager.Pointer()->Unregister(this);
-}
-
-// static
-bool DiscardableMemoryEmulated::ReduceMemoryUsage() {
-  return g_manager.Pointer()->ReduceMemoryUsage();
-}
-
-// static
-void DiscardableMemoryEmulated::ReduceMemoryUsageUntilWithinLimit(
-    size_t bytes) {
-  g_manager.Pointer()->ReduceMemoryUsageUntilWithinLimit(bytes);
-}
-
-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;
-
-  is_locked_ = true;
-  return purged ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
-                : DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
-}
-
-void DiscardableMemoryEmulated::Unlock() {
-  DCHECK(is_locked_);
-  g_manager.Pointer()->ReleaseLock(this);
-  is_locked_ = false;
-}
-
-void* DiscardableMemoryEmulated::Memory() const {
-  DCHECK(is_locked_);
-  DCHECK(memory_);
-  return memory_.get();
-}
-
-bool DiscardableMemoryEmulated::AllocateAndAcquireLock() {
-  if (memory_)
-    return true;
-
-  memory_.reset(new uint8[bytes_]);
-  return false;
-}
-
-void DiscardableMemoryEmulated::Purge() {
-  memory_.reset();
-}
-
-}  // namespace internal
-}  // namespace base