Introduce AudioIPCFactory.

content/renderer/media/audio_ipc_factory.cc

+// Copyright 2017 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 "content/renderer/media/audio_ipc_factory.h"
+
+#include <utility>
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/single_thread_task_runner.h"
+#include "content/renderer/media/audio_message_filter.h"
+#include "content/renderer/media/mojo_audio_output_ipc.h"
+#include "services/service_manager/public/cpp/interface_provider.h"
+
+namespace content {
+
+AudioIPCFactory* AudioIPCFactory::instance_ = nullptr;
+
+AudioIPCFactory::AudioIPCFactory(
+    scoped_refptr<AudioMessageFilter> audio_message_filter,
+    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
+    : audio_message_filter_(std::move(audio_message_filter)),
+      io_task_runner_(std::move(io_task_runner)) {
+  // TODO(maxmorin): In the future, use a feature to control whether
+  // audio_message_filter should be used.
+  DCHECK(!instance_);
+  instance_ = this;
+}
+
+AudioIPCFactory::~AudioIPCFactory() {
+  // Allow destruction in tests.
+  DCHECK(factory_ptrs_.empty());
+  DCHECK_EQ(instance_, this);
+  instance_ = nullptr;
+}
+
+std::unique_ptr<media::AudioOutputIPC> AudioIPCFactory::CreateAudioOutputIPC(
+    int frame_id) const {
+  if (UsingMojoFactories()) {
+    // Unretained is safe due to the contract at the top of the header file.
+    return base::MakeUnique<MojoAudioOutputIPC>(base::BindRepeating(
+        &AudioIPCFactory::GetRemoteFactory, base::Unretained(this), frame_id));
+  }
+  return audio_message_filter_->CreateAudioOutputIPC(frame_id);
+}
+
+void AudioIPCFactory::MaybeRegisterRemoteFactory(
+    int frame_id,
+    service_manager::InterfaceProvider* interface_provider) {
+  if (!UsingMojoFactories())
+    return;
+  mojom::RendererAudioOutputStreamFactoryPtr factory_ptr;
+  interface_provider->GetInterface(&factory_ptr);
+  // PassInterface unbinds the message pipe from the current thread. This
+  // allows us to bind it to the IO thread.
+  // Unretained is safe due to the contract at the top of the header file.
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::BindOnce(&AudioIPCFactory::RegisterRemoteFactoryOnIOThread,
+                     base::Unretained(this), frame_id,
+                     factory_ptr.PassInterface()));
+}
+
+void AudioIPCFactory::MaybeDeregisterRemoteFactory(int frame_id) {
+  if (!UsingMojoFactories())
+    return;
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::BindOnce(&AudioIPCFactory::MaybeDeregisterRemoteFactoryOnIOThread,
+                     base::Unretained(this), frame_id));
+}
+
+mojom::RendererAudioOutputStreamFactory* AudioIPCFactory::GetRemoteFactory(
+    int frame_id) const {
+  DCHECK(io_task_runner_->BelongsToCurrentThread());
+  DCHECK(UsingMojoFactories());
+  auto it = factory_ptrs_.find(frame_id);
+  return it == factory_ptrs_.end() ? nullptr : it->second.get();
+}
+
+void AudioIPCFactory::RegisterRemoteFactoryOnIOThread(
+    int frame_id,
+    mojom::RendererAudioOutputStreamFactoryPtrInfo factory_ptr_info) {
+  DCHECK(io_task_runner_->BelongsToCurrentThread());
+  DCHECK(UsingMojoFactories());
+  std::pair<StreamFactoryMap::iterator, bool> emplace_result =
+      factory_ptrs_.emplace(frame_id,
+                            mojo::MakeProxy(std::move(factory_ptr_info)));
+
+  DCHECK(emplace_result.second) << "Attempt to register a factory for a "
+                                   "frame which already has a factory "
+                                   "registered.";
+
+  auto& emplaced_factory = emplace_result.first->second;
+  DCHECK(emplaced_factory.is_bound())
+      << "Factory is not bound to a remote implementation.";
+
+  // Unretained is safe because |this| owns the binding, so a connection error
+  // cannot trigger after destruction.
+  emplaced_factory.set_connection_error_handler(
+      base::Bind(&AudioIPCFactory::MaybeDeregisterRemoteFactory,
+                 base::Unretained(this), frame_id));
+}
+
+void AudioIPCFactory::MaybeDeregisterRemoteFactoryOnIOThread(int frame_id) {
+  DCHECK(io_task_runner_->BelongsToCurrentThread());
+  DCHECK(UsingMojoFactories());
+  // This function can be called both by the frame and the connection error
+  // handler of the factory pointer. Calling erase multiple times even though
+  // there is nothing to erase is safe, so we don't have to handle this in any
+  // particular way.
+  factory_ptrs_.erase(frame_id);
+}
+
+bool AudioIPCFactory::UsingMojoFactories() const {
+  return audio_message_filter_ == nullptr;
+}
+
+}  // namespace content