content/common/child_process.mojom

// Copyright 2019 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.

module content.mojom;

import "components/tracing/common/background_tracing_agent.mojom";
import "mojo/public/mojom/base/generic_pending_receiver.mojom";
import "services/service_manager/public/mojom/service.mojom";

// The primordial interface child processes use to push requests to their
// browser-side host object.
interface ChildProcessHost {
  // Requests that the browser bind |receiver| on behalf of the child process.
  // Whether or not the interface type encapsulated by |receiver| is supported
  // depends on the process type and potentially on the Content embedder.
  BindHostReceiver(mojo_base.mojom.GenericPendingReceiver receiver);
};

// An interface bound on the browser's IO thread to accept a ChildProcessHost
// receiver from the child process. A remote to this interface is sent to child
// processes via |ChildProcess.Initialize()| so that the child process may in
// turn send back a ChildProcessHost receiver for the browser to bind. This
// allows the child process to begin queuing messages on its ChildProcessHost
// immediately upon startup without first waiting for
// |ChildProcess.Initialize()|.
//
// NOTE: This is a separate interface and message rather than a simple reply to
// |ChildProcess.Initialize()| because RenderProcessHostImpl binds its
// ChildProcess remote on the main thread, and the ChildProcessHost receiver
// needs to be accepted and bound on the IO thread without a main-thread hop.
interface ChildProcessHostBootstrap {
  BindProcessHost(pending_receiver<ChildProcessHost> receiver);
};

// A control interface the browser uses to drive the behavior of all types of
// Content child processes.
interface ChildProcess {
  // The first message sent by the process host to the child process. This is
  // sent to allow the child process to bootstrap its own ChildProcessHost
  // interface, to which it may have already queued messages.
  Initialize(pending_remote<ChildProcessHostBootstrap> boostrap);

  // Tells the child process that it's safe to shutdown.
  ProcessShutdown();

  // Requests the child process send its Mach task port to the caller.
  [EnableIf=is_mac]
  GetTaskPort() => (handle task_port);

  // Tells the child process to begin or end IPC message logging.
  [EnableIf=ipc_logging]
  SetIPCLoggingEnabled(bool on);

  // Used to configure triggering for background tracing of child processes.
  GetBackgroundTracingAgentProvider(
      pending_receiver<tracing.mojom.BackgroundTracingAgentProvider> receiver);

  // Force the child process to crash immediately (i.e. a hard crash, no
  // cleanup, generating a crash report).
  CrashHungProcess();

  // Tells the child process to run an instance of a service named
  // |service_name|, binding it to |receiver|. This is used by the browser to
  // support launching of packaged services within Utility or GPU processes.
  //
  // DEPRECATED: |BindServiceInterface()| should be used instead. This will be
  // removed soon.
  RunService(string service_name,
             pending_receiver<service_manager.mojom.Service> receiver);

  // Requests that the process bind a receiving pipe targeting the service
  // interface named by |receiver|.
  //
  // TODO(crbug.com/977637): Rename this to |RunService()| once the above method
  // is removed.
  BindServiceInterface(mojo_base.mojom.GenericPendingReceiver receiver);

  // Requests that the process bind a receiving pipe targeting the interface
  // named by |receiver|. Unlike |BindServiceInterface()| this may be used to
  // bind arbitrary interfaces on many different types of child processes.
  // Calls to this method generally end up in
  // |ChildThreadImpl::OnBindReceiver()|.
  //
  // Whether or not the interface type encapsulated by |receiver| is supported
  // depends on the process type and potentially on the Content embedder.
  BindReceiver(mojo_base.mojom.GenericPendingReceiver receiver);
};