Move ChannelMojo bindings to a custom multiplex router

ipc/ipc_mojo_bootstrap.cc

Index: ipc/ipc_mojo_bootstrap.cc
diff --git a/ipc/ipc_mojo_bootstrap.cc b/ipc/ipc_mojo_bootstrap.cc
index ba0ea46fe5750ae93e7a0741f09f88f60a8dd04a..dc8ffdc8134dce5d8b6b962f8cadfadcd4e3dd00 100644
--- a/ipc/ipc_mojo_bootstrap.cc
+++ b/ipc/ipc_mojo_bootstrap.cc
@@ -5,6 +5,9 @@
 #include "ipc/ipc_mojo_bootstrap.h"
 
 #include <stdint.h>
+
+#include <map>
+#include <memory>
 #include <utility>
 
 #include "base/callback.h"
@@ -12,15 +15,603 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/process/process_handle.h"
+#include "base/single_thread_task_runner.h"
+#include "base/stl_util.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "ipc/ipc_message_utils.h"
 #include "ipc/ipc_platform_file.h"
+#include "mojo/public/cpp/bindings/associated_group.h"
+#include "mojo/public/cpp/bindings/associated_group_controller.h"
 #include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/public/cpp/bindings/connector.h"
+#include "mojo/public/cpp/bindings/interface_endpoint_client.h"
+#include "mojo/public/cpp/bindings/interface_endpoint_controller.h"
+#include "mojo/public/cpp/bindings/interface_id.h"
+#include "mojo/public/cpp/bindings/message_header_validator.h"
+#include "mojo/public/cpp/bindings/pipe_control_message_handler.h"
+#include "mojo/public/cpp/bindings/pipe_control_message_handler_delegate.h"
+#include "mojo/public/cpp/bindings/pipe_control_message_proxy.h"
 
 namespace IPC {
 
 namespace {
 
+class ChannelAssociatedGroupController
+    : public mojo::AssociatedGroupController,
+      public mojo::MessageReceiver,
+      public mojo::PipeControlMessageHandlerDelegate {
+ public:
+  ChannelAssociatedGroupController(bool set_interface_id_namespace_bit,
+                                   mojo::ScopedMessagePipeHandle handle)
+      : mojo::AssociatedGroupController(base::ThreadTaskRunnerHandle::Get()),
+        task_runner_(base::ThreadTaskRunnerHandle::Get()),
+        id_namespace_mask_(set_interface_id_namespace_bit ?
+              mojo::kInterfaceIdNamespaceMask : 0),
+        associated_group_(CreateAssociatedGroup()),
+        connector_(std::move(handle), mojo::Connector::SINGLE_THREADED_SEND,
+                   base::ThreadTaskRunnerHandle::Get()),
+        header_validator_(
+            "IPC::mojom::Bootstrap [master] MessageHeaderValidator", this),
+        control_message_handler_(this),
+        control_message_proxy_(&connector_) {
+    connector_.set_incoming_receiver(&header_validator_);
+    connector_.set_connection_error_handler(
+        base::Bind(&ChannelAssociatedGroupController::OnPipeError,
+                   base::Unretained(this)));
+    control_message_handler_.SetDescription(
+        "IPC::mojom::Bootstrap [master] PipeControlMessageHandler");
+  }
+
+  mojo::AssociatedGroup* associated_group() { return associated_group_.get(); }
+
+  void ShutDown() {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    connector_.CloseMessagePipe();
+    OnPipeError();
+    associated_group_.reset();
+  }
+
+  void SetProxyTaskRunner(
+      scoped_refptr<base::SingleThreadTaskRunner> proxy_task_runner) {
+    proxy_task_runner_ = proxy_task_runner;
+  }
+
+  // mojo::AssociatedGroupController:
+  void CreateEndpointHandlePair(
+      mojo::ScopedInterfaceEndpointHandle* local_endpoint,
+      mojo::ScopedInterfaceEndpointHandle* remote_endpoint) override {
+    base::AutoLock locker(lock_);
+    uint32_t id = 0;
+    do {
+      if (next_interface_id_ >= mojo::kInterfaceIdNamespaceMask)
+        next_interface_id_ = 1;
+      id = (next_interface_id_++) | id_namespace_mask_;
+    } while (ContainsKey(endpoints_, id));
+
+    Endpoint* endpoint = new Endpoint(this, id);
+    if (encountered_error_)
+      endpoint->set_peer_closed();
+    endpoints_.insert({ id, endpoint });
+
+    *local_endpoint = CreateScopedInterfaceEndpointHandle(id, true);
+    *remote_endpoint = CreateScopedInterfaceEndpointHandle(id, false);
+  }
+
+  mojo::ScopedInterfaceEndpointHandle CreateLocalEndpointHandle(
+      mojo::InterfaceId id) override {
+    if (!mojo::IsValidInterfaceId(id))
+      return mojo::ScopedInterfaceEndpointHandle();
+
+    base::AutoLock locker(lock_);
+    bool inserted = false;
+    Endpoint* endpoint = FindOrInsertEndpoint(id, &inserted);
+    if (inserted && encountered_error_)
+      endpoint->set_peer_closed();
+
+    return CreateScopedInterfaceEndpointHandle(id, true);
+  }
+
+  void CloseEndpointHandle(mojo::InterfaceId id, bool is_local) override {
+    if (!mojo::IsValidInterfaceId(id))
+      return;
+
+    base::AutoLock locker(lock_);
+    if (!is_local) {
+      DCHECK(ContainsKey(endpoints_, id));
+      DCHECK(!mojo::IsMasterInterfaceId(id));
+      control_message_proxy_.NotifyEndpointClosedBeforeSent(id);
+      return;
+    }
+
+    DCHECK(ContainsKey(endpoints_, id));
+    Endpoint* endpoint = endpoints_[id].get();
+    DCHECK(!endpoint->client());
+    DCHECK(!endpoint->closed());
+    MarkClosedAndMaybeRemove(endpoint);
+
+    if (!mojo::IsMasterInterfaceId(id))
+      control_message_proxy_.NotifyPeerEndpointClosed(id);
+  }
+
+  mojo::InterfaceEndpointController* AttachEndpointClient(
+      const mojo::ScopedInterfaceEndpointHandle& handle,
+      mojo::InterfaceEndpointClient* client,
+      scoped_refptr<base::SingleThreadTaskRunner> runner) override {
+    const mojo::InterfaceId id = handle.id();
+
+    DCHECK(mojo::IsValidInterfaceId(id));
+    DCHECK(client);
+
+    base::AutoLock locker(lock_);
+    DCHECK(ContainsKey(endpoints_, id));
+
+    Endpoint* endpoint = endpoints_[id].get();
+    endpoint->AttachClient(client, std::move(runner));
+
+    if (endpoint->peer_closed())
+      NotifyEndpointOfError(endpoint, true /* force_async */);
+
+    return endpoint;
+  }
+
+  void DetachEndpointClient(
+      const mojo::ScopedInterfaceEndpointHandle& handle) override {
+    const mojo::InterfaceId id = handle.id();
+
+    DCHECK(mojo::IsValidInterfaceId(id));
+
+    base::AutoLock locker(lock_);
+    DCHECK(ContainsKey(endpoints_, id));
+
+    Endpoint* endpoint = endpoints_[id].get();
+    endpoint->DetachClient();
+  }
+
+  void RaiseError() override {
+    if (task_runner_->BelongsToCurrentThread()) {
+      connector_.RaiseError();
+    } else {
+      task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(&ChannelAssociatedGroupController::RaiseError, this));
+    }
+  }
+
+ private:
+  class Endpoint;
+  friend class Endpoint;
+
+  class Endpoint : public base::RefCountedThreadSafe<Endpoint>,
+                   public mojo::InterfaceEndpointController {
+   public:
+    Endpoint(ChannelAssociatedGroupController* controller, mojo::InterfaceId id)
+        : controller_(controller), id_(id) {}
+
+    mojo::InterfaceId id() const { return id_; }
+
+    bool closed() const {
+      controller_->lock_.AssertAcquired();
+      return closed_;
+    }
+
+    void set_closed() {
+      controller_->lock_.AssertAcquired();
+      closed_ = true;
+    }
+
+    bool peer_closed() const {
+      controller_->lock_.AssertAcquired();
+      return peer_closed_;
+    }
+
+    void set_peer_closed() {
+      controller_->lock_.AssertAcquired();
+      peer_closed_ = true;
+    }
+
+    base::SingleThreadTaskRunner* task_runner() const {
+      return task_runner_.get();
+    }
+
+    mojo::InterfaceEndpointClient* client() const {
+      controller_->lock_.AssertAcquired();
+      return client_;
+    }
+
+    void AttachClient(mojo::InterfaceEndpointClient* client,
+                      scoped_refptr<base::SingleThreadTaskRunner> runner) {
+      controller_->lock_.AssertAcquired();
+      DCHECK(!client_);
+      DCHECK(!closed_);
+      DCHECK(runner->BelongsToCurrentThread());
+
+      task_runner_ = std::move(runner);
+      client_ = client;
+    }
+
+    void DetachClient() {
+      controller_->lock_.AssertAcquired();
+      DCHECK(client_);
+      DCHECK(task_runner_->BelongsToCurrentThread());
+      DCHECK(!closed_);
+
+      task_runner_ = nullptr;
+      client_ = nullptr;
+    }
+
+    // mojo::InterfaceEndpointController:
+    bool SendMessage(mojo::Message* message) override {
+      DCHECK(task_runner_->BelongsToCurrentThread());
+      message->set_interface_id(id_);
+      return controller_->SendMessage(message);
+    }
+
+    void AllowWokenUpBySyncWatchOnSameThread() override {
+      DCHECK(task_runner_->BelongsToCurrentThread());
+
+      // TODO(rockot): Implement sync waiting.
+      NOTREACHED();
+    }
+
+    bool SyncWatch(const bool* should_stop) override {
+      DCHECK(task_runner_->BelongsToCurrentThread());
+
+      // It's not legal to make sync calls from the master endpoint's thread,
+      // and in fact they must only happen from the proxy task runner.
+      DCHECK(!controller_->task_runner_->BelongsToCurrentThread());
+      DCHECK(controller_->proxy_task_runner_->BelongsToCurrentThread());
+
+      // TODO(rockot): Implement sync waiting.
+      NOTREACHED();
+      return false;
+    }
+
+   private:
+    friend class base::RefCountedThreadSafe<Endpoint>;
+
+    ~Endpoint() override {}
+
+    ChannelAssociatedGroupController* const controller_;
+    const mojo::InterfaceId id_;
+
+    bool closed_ = false;
+    bool peer_closed_ = false;
+    mojo::InterfaceEndpointClient* client_ = nullptr;
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+    DISALLOW_COPY_AND_ASSIGN(Endpoint);
+  };
+
+  ~ChannelAssociatedGroupController() override {
+    base::AutoLock locker(lock_);
+
+    for (auto iter = endpoints_.begin(); iter != endpoints_.end();) {
+      Endpoint* endpoint = iter->second.get();
+      ++iter;
+
+      DCHECK(endpoint->closed());
+      MarkPeerClosedAndMaybeRemove(endpoint);
+    }
+
+    DCHECK(endpoints_.empty());
+  }
+
+  bool SendMessage(mojo::Message* message) {
+    if (task_runner_->BelongsToCurrentThread()) {
+      DCHECK(thread_checker_.CalledOnValidThread());
+      return connector_.Accept(message);
+    } else {
+      // We always post tasks to the master endpoint thread when called from the
+      // proxy thread in order to simulate IPC::ChannelProxy::Send behavior.
+      DCHECK(proxy_task_runner_ &&
+             proxy_task_runner_->BelongsToCurrentThread());
+      std::unique_ptr<mojo::Message> passed_message(new mojo::Message);
+      message->MoveTo(passed_message.get());
+      task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(
+              &ChannelAssociatedGroupController::SendMessageOnMasterThread,
+              this, base::Passed(&passed_message)));
+      return true;
+    }
+  }
+
+  void SendMessageOnMasterThread(std::unique_ptr<mojo::Message> message) {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    if (!SendMessage(message.get()))
+      RaiseError();
+  }
+
+  void OnPipeError() {
+    DCHECK(thread_checker_.CalledOnValidThread());
+
+    // We keep |this| alive here because it's possible for the notifications
+    // below to release all other references.
+    scoped_refptr<ChannelAssociatedGroupController> keepalive(this);
+
+    base::AutoLock locker(lock_);
+    encountered_error_ = true;
+
+    std::vector<scoped_refptr<Endpoint>> endpoints_to_notify;
+    for (auto iter = endpoints_.begin(); iter != endpoints_.end();) {
+      Endpoint* endpoint = iter->second.get();
+      ++iter;
+
+      if (endpoint->client())
+        endpoints_to_notify.push_back(endpoint);
+
+      MarkPeerClosedAndMaybeRemove(endpoint);
+    }
+
+    for (auto& endpoint : endpoints_to_notify) {
+      // Because an notification may in turn detach any endpoint, we have to
+      // check each client again here.
+      if (endpoint->client())
+        NotifyEndpointOfError(endpoint.get(), false /* force_async */);
+    }
+  }
+
+  void NotifyEndpointOfError(Endpoint* endpoint, bool force_async) {
+    lock_.AssertAcquired();
+    DCHECK(endpoint->task_runner() && endpoint->client());
+    if (endpoint->task_runner()->BelongsToCurrentThread() && !force_async) {
+      mojo::InterfaceEndpointClient* client = endpoint->client();
+
+      base::AutoUnlock unlocker(lock_);
+      client->NotifyError();
+    } else {
+      endpoint->task_runner()->PostTask(
+          FROM_HERE,
+          base::Bind(&ChannelAssociatedGroupController
+                ::NotifyEndpointOfErrorOnEndpointThread, this,
+                make_scoped_refptr(endpoint)));
+    }
+  }
+
+  void NotifyEndpointOfErrorOnEndpointThread(scoped_refptr<Endpoint> endpoint) {
+    base::AutoLock locker(lock_);
+    if (!endpoint->client())
+      return;
+    DCHECK(endpoint->task_runner()->BelongsToCurrentThread());
+    NotifyEndpointOfError(endpoint.get(), false /* force_async */);
+  }
+
+  void MarkClosedAndMaybeRemove(Endpoint* endpoint) {
+    lock_.AssertAcquired();
+    endpoint->set_closed();
+    if (endpoint->closed() && endpoint->peer_closed())
+      endpoints_.erase(endpoint->id());
+  }
+
+  void MarkPeerClosedAndMaybeRemove(Endpoint* endpoint) {
+    lock_.AssertAcquired();
+    endpoint->set_peer_closed();
+    if (endpoint->closed() && endpoint->peer_closed())
+      endpoints_.erase(endpoint->id());
+  }
+
+  Endpoint* FindOrInsertEndpoint(mojo::InterfaceId id, bool* inserted) {
+    lock_.AssertAcquired();
+    DCHECK(!inserted || !*inserted);
+
+    auto iter = endpoints_.find(id);
+    if (iter != endpoints_.end())
+      return iter->second.get();
+
+    Endpoint* endpoint = new Endpoint(this, id);
+    endpoints_.insert({ id, endpoint });
+    if (inserted)
+      *inserted = true;
+    return endpoint;
+  }
+
+  // mojo::MessageReceiver:
+  bool Accept(mojo::Message* message) override {
+    DCHECK(thread_checker_.CalledOnValidThread());
+
+    if (mojo::PipeControlMessageHandler::IsPipeControlMessage(message)) {
+      if (!control_message_handler_.Accept(message))
+        RaiseError();
+      return true;
+    }
+
+    mojo::InterfaceId id = message->interface_id();
+    DCHECK(mojo::IsValidInterfaceId(id));
+
+    base::AutoLock locker(lock_);
+    bool inserted = false;
+    Endpoint* endpoint = FindOrInsertEndpoint(id, &inserted);
+    if (inserted) {
+      MarkClosedAndMaybeRemove(endpoint);
+      if (!mojo::IsMasterInterfaceId(id))
+        control_message_proxy_.NotifyPeerEndpointClosed(id);
+      return true;
+    }
+
+    if (endpoint->closed())
+      return true;
+
+    mojo::InterfaceEndpointClient* client = endpoint->client();
+    if (!client || !endpoint->task_runner()->BelongsToCurrentThread()) {
+      // No client has been bound yet or the client runs tasks on another
+      // thread. We assume the other thread must always be the one on which
+      // |proxy_task_runner_| runs tasks, since that's the only valid scenario.
+      //
+      // If the client is not yet bound, it must be bound by the time this task
+      // runs or else it's programmer error.
+      DCHECK(proxy_task_runner_);
+      CHECK(false);
+      std::unique_ptr<mojo::Message> passed_message(new mojo::Message);
+      message->MoveTo(passed_message.get());
+      proxy_task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(&ChannelAssociatedGroupController::AcceptOnProxyThread,
+                     this, base::Passed(&passed_message)));
+      return true;
+    }
+
+    // We do not expect to receive sync responses on the master endpoint thread.
+    // If it's happening, it's a bug.
+    DCHECK(!message->has_flag(mojo::Message::kFlagIsSync));
+
+    bool result = false;
+    {
+      base::AutoUnlock unlocker(lock_);
+      result = client->HandleIncomingMessage(message);
+    }
+
+    if (!result)
+      RaiseError();
+
+    return true;
+  }
+
+  void AcceptOnProxyThread(std::unique_ptr<mojo::Message> message) {
+    DCHECK(proxy_task_runner_->BelongsToCurrentThread());
+
+    // TODO(rockot): Implement this.
+    NOTREACHED();
+  }
+
+  // mojo::PipeControlMessageHandlerDelegate:
+  bool OnPeerAssociatedEndpointClosed(mojo::InterfaceId id) override {
+    DCHECK(thread_checker_.CalledOnValidThread());
+
+    if (mojo::IsMasterInterfaceId(id))
+      return false;
+
+    base::AutoLock locker(lock_);
+    scoped_refptr<Endpoint> endpoint = FindOrInsertEndpoint(id, nullptr);
+    if (!endpoint->peer_closed()) {
+      if (endpoint->client())
+        NotifyEndpointOfError(endpoint.get(), false /* force_async */);
+      MarkPeerClosedAndMaybeRemove(endpoint.get());
+    }
+
+    return true;
+  }
+
+  bool OnAssociatedEndpointClosedBeforeSent(mojo::InterfaceId id) override {
+    DCHECK(thread_checker_.CalledOnValidThread());
+
+    if (mojo::IsMasterInterfaceId(id))
+      return false;
+
+    base::AutoLock locker(lock_);
+    Endpoint* endpoint = FindOrInsertEndpoint(id, nullptr);
+    DCHECK(!endpoint->closed());
+    MarkClosedAndMaybeRemove(endpoint);
+    control_message_proxy_.NotifyPeerEndpointClosed(id);
+    return true;
+  }
+
+  // Checked in places which must be run on the master endpoint's thread.
+  base::ThreadChecker thread_checker_;
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> proxy_task_runner_;
+  const uint32_t id_namespace_mask_;
+  std::unique_ptr<mojo::AssociatedGroup> associated_group_;
+  mojo::Connector connector_;
+  mojo::MessageHeaderValidator header_validator_;
+  mojo::PipeControlMessageHandler control_message_handler_;
+
+  // Guards the fields below for thread-safe access.
+  base::Lock lock_;
+
+  bool encountered_error_ = false;
+  uint32_t next_interface_id_ = 1;
+  std::map<uint32_t, scoped_refptr<Endpoint>> endpoints_;
+  mojo::PipeControlMessageProxy control_message_proxy_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChannelAssociatedGroupController);
+};
+
+class BootstrapMasterProxy {
+ public:
+  BootstrapMasterProxy() {}
+  ~BootstrapMasterProxy() {
+    endpoint_client_.reset();
+    proxy_.reset();
+    if (controller_)
+      controller_->ShutDown();
+  }
+
+  void Bind(mojo::ScopedMessagePipeHandle handle) {
+    DCHECK(!controller_);
+    controller_ = new ChannelAssociatedGroupController(true, std::move(handle));
+    endpoint_client_.reset(new mojo::InterfaceEndpointClient(
+        controller_->CreateLocalEndpointHandle(mojo::kMasterInterfaceId),
+        nullptr,
+        base::MakeUnique<typename mojom::Bootstrap::ResponseValidator_>(),
+        false, base::ThreadTaskRunnerHandle::Get()));
+    proxy_.reset(new mojom::BootstrapProxy(endpoint_client_.get()));
+    proxy_->serialization_context()->group_controller = controller_;
+  }
+
+  void set_connection_error_handler(const base::Closure& handler) {
+    DCHECK(endpoint_client_);
+    endpoint_client_->set_connection_error_handler(handler);
+  }
+
+  mojo::AssociatedGroup* associated_group() {
+    DCHECK(controller_);
+    return controller_->associated_group();
+  }
+
+  mojom::Bootstrap* operator->() {
+    DCHECK(proxy_);
+    return proxy_.get();
+  }
+
+ private:
+  std::unique_ptr<mojom::BootstrapProxy> proxy_;
+  scoped_refptr<ChannelAssociatedGroupController> controller_;
+  std::unique_ptr<mojo::InterfaceEndpointClient> endpoint_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(BootstrapMasterProxy);
+};
+
+class BootstrapMasterBinding {
+ public:
+  explicit BootstrapMasterBinding(mojom::Bootstrap* impl) {
+    stub_.set_sink(impl);
+  }
+
+  ~BootstrapMasterBinding() {
+    endpoint_client_.reset();
+    if (controller_)
+      controller_->ShutDown();
+  }
+
+  void set_connection_error_handler(const base::Closure& handler) {
+    DCHECK(endpoint_client_);
+    endpoint_client_->set_connection_error_handler(handler);
+  }
+
+  void Bind(mojo::ScopedMessagePipeHandle handle) {
+    DCHECK(!controller_);
+    controller_ =
+        new ChannelAssociatedGroupController(false, std::move(handle));
+    stub_.serialization_context()->group_controller = controller_;
+
+    endpoint_client_.reset(new mojo::InterfaceEndpointClient(
+        controller_->CreateLocalEndpointHandle(mojo::kMasterInterfaceId),
+        &stub_,
+        base::MakeUnique<typename mojom::Bootstrap::RequestValidator_>(),
+        false, base::ThreadTaskRunnerHandle::Get()));
+  }
+
+ private:
+  mojom::BootstrapStub stub_;
+  scoped_refptr<ChannelAssociatedGroupController> controller_;
+  std::unique_ptr<mojo::InterfaceEndpointClient> endpoint_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(BootstrapMasterBinding);
+};
+
 // MojoBootstrap for the server process. You should create the instance
 // using MojoBootstrap::Create().
 class MojoServerBootstrap : public MojoBootstrap {
@@ -33,7 +624,7 @@ class MojoServerBootstrap : public MojoBootstrap {
 
   void OnInitDone(int32_t peer_pid);
 
-  mojom::BootstrapPtr bootstrap_;
+  BootstrapMasterProxy bootstrap_;
   IPC::mojom::ChannelAssociatedPtrInfo send_channel_;
   IPC::mojom::ChannelAssociatedRequest receive_channel_request_;
 
@@ -45,7 +636,7 @@ MojoServerBootstrap::MojoServerBootstrap() = default;
 void MojoServerBootstrap::Connect() {
   DCHECK_EQ(state(), STATE_INITIALIZED);
 
-  bootstrap_.Bind(mojom::BootstrapPtrInfo(TakeHandle(), 0));
+  bootstrap_.Bind(TakeHandle());
   bootstrap_.set_connection_error_handler(
       base::Bind(&MojoServerBootstrap::Fail, base::Unretained(this)));
 
@@ -96,7 +687,7 @@ class MojoClientBootstrap : public MojoBootstrap, public mojom::Bootstrap {
             int32_t peer_pid,
             const InitCallback& callback) override;
 
-  mojo::Binding<mojom::Bootstrap> binding_;
+  BootstrapMasterBinding binding_;
 
   DISALLOW_COPY_AND_ASSIGN(MojoClientBootstrap);
 };