Update from https://crrev.com/320931

base/test/test_discardable_memory_shmem_allocator.cc

+// Copyright 2015 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/test/test_discardable_memory_shmem_allocator.h"
+
+#include <stdint.h>
+
+namespace base {
+namespace {
+
+class DiscardableMemoryShmemChunkImpl : public DiscardableMemoryShmemChunk {
+ public:
+  explicit DiscardableMemoryShmemChunkImpl(size_t size)
+      : memory_(new uint8_t[size]) {}
+
+  // Overridden from DiscardableMemoryShmemChunk:
+  bool Lock() override { return false; }
+  void Unlock() override {}
+  void* Memory() const override { return memory_.get(); }
+
+ private:
+  scoped_ptr<uint8_t[]> memory_;
+};
+
+}  // namespace
+
+TestDiscardableMemoryShmemAllocator::TestDiscardableMemoryShmemAllocator() {
+}
+
+TestDiscardableMemoryShmemAllocator::~TestDiscardableMemoryShmemAllocator() {
+}
+
+scoped_ptr<DiscardableMemoryShmemChunk>
+TestDiscardableMemoryShmemAllocator::AllocateLockedDiscardableMemory(
+    size_t size) {
+  return make_scoped_ptr(new DiscardableMemoryShmemChunkImpl(size));
+}
+
+}  // namespace base