discardable_memory: Using mojo IPC to replace Chrome IPC

components/discardable_memory/service/discardable_shared_memory_manager_proxy.cc

+// Copyright 2016 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 "components/discardable_memory/service/discardable_shared_memory_manager_proxy.h"
+
+#include "components/discardable_memory/service/discardable_shared_memory_manager.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "mojo/public/cpp/system/platform_handle.h"
+
+namespace discardable_memory {
+
+namespace {
+int last_client_id = 0;

[reveman, 2016/11/11 20:17:27]

Can this be in the ::discardable_memory::DiscardableSharedMemoryManager instance
instead? If we need to keep it here then use:
base::StaticAtomicSequenceNumber g_next_client_id

[Peng, 2016/11/11 22:50:35]

Done.

+}
+
+DiscardableSharedMemoryManagerProxy::DiscardableSharedMemoryManagerProxy()
+    : client_id_(++last_client_id) {}
+
+DiscardableSharedMemoryManagerProxy::~DiscardableSharedMemoryManagerProxy() {
+  ::discardable_memory::DiscardableSharedMemoryManager::current()

[reveman, 2016/11/11 20:17:26]

Can this class have a pointer to the manager instance instead of relying on
::current()?

[Peng, 2016/11/11 22:50:35]

Done.

+      ->ClientRemoved(client_id_);
+}
+
+// static
+void DiscardableSharedMemoryManagerProxy::Create(
+    mojom::DiscardableSharedMemoryManagerRequest request) {
+  mojo::MakeStrongBinding(
+      base::MakeUnique<DiscardableSharedMemoryManagerProxy>(),
+      std::move(request));
+}
+
+void DiscardableSharedMemoryManagerProxy::AllocateLockedDiscardableSharedMemory(
+    uint32_t size,
+    int32_t id,
+    const AllocateLockedDiscardableSharedMemoryCallback& callback) {
+  base::SharedMemoryHandle handle;
+  ::discardable_memory::DiscardableSharedMemoryManager::current()
+      ->AllocateLockedDiscardableSharedMemoryForClient(client_id_, size, id,
+                                                       &handle);
+  mojo::ScopedSharedBufferHandle memory;
+  if (handle != base::SharedMemory::NULLHandle()) {
+    memory = mojo::WrapSharedMemoryHandle(handle, size, false /* ready_only */);
+  }
+  return callback.Run(std::move(memory));
+}
+
+void DiscardableSharedMemoryManagerProxy::DeletedDiscardableSharedMemory(
+    int32_t id) {
+  ::discardable_memory::DiscardableSharedMemoryManager::current()
+      ->ClientDeletedDiscardableSharedMemory(id, client_id_);
+}
+
+}  // namespace discardable_memory