Use DiscardableMemoryManager on Android.

base/memory/discardable_memory_ashmem.cc

Index: base/memory/discardable_memory_ashmem.cc
diff --git a/base/memory/discardable_memory_ashmem.cc b/base/memory/discardable_memory_ashmem.cc
new file mode 100644
index 0000000000000000000000000000000000000000..43f07b618cabdcee625c9d6475f67b1b56949c35
--- /dev/null
+++ b/base/memory/discardable_memory_ashmem.cc
@@ -0,0 +1,54 @@
+// Copyright 2014 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_ashmem.h"
+
+#include "base/lazy_instance.h"
+#include "base/memory/discardable_memory_allocation_ashmem_factory.h"
+#include "base/memory/discardable_memory_manager.h"
+
+namespace base {
+namespace internal {
+
+DiscardableMemoryAshmem::DiscardableMemoryAshmem(
+    DiscardableMemoryManager* manager,
+    size_t size)
+    : manager_(manager),
+      allocation_id_(manager->Register(size)),
+      memory_(NULL) {
+}
+
+DiscardableMemoryAshmem::~DiscardableMemoryAshmem() {
+  manager_->Unregister(allocation_id_);
+}
+
+bool DiscardableMemoryAshmem::Initialize() {
+  return Lock() == DISCARDABLE_MEMORY_LOCK_STATUS_PURGED;
+}
+
+DiscardableMemoryLockStatus DiscardableMemoryAshmem::Lock() {
+  DCHECK(!memory_);
+
+  bool purged = false;
+  memory_ = manager_->Lock(allocation_id_, &purged);
+  if (!memory_)
+    return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
+
+  return purged ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
+                : DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
+}
+
+void DiscardableMemoryAshmem::Unlock() {
+  DCHECK(memory_);
+  manager_->Unlock(allocation_id_);
+  memory_ = NULL;
+}
+
+void* DiscardableMemoryAshmem::Memory() const {
+  DCHECK(memory_);
+  return memory_;
+}
+
+}  // namespace internal
+}  // namespace base