Make ChildProcessHost be used through an interface in content/public, instead of by inheritence.

content/common/child_process_host.h

-// Copyright (c) 2011 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.
-
-#ifndef CONTENT_COMMON_CHILD_PROCESS_HOST_H_
-#define CONTENT_COMMON_CHILD_PROCESS_HOST_H_
-#pragma once
-
-#include <string>
-#include <vector>
-
-#include "build/build_config.h"
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/singleton.h"
-#include "base/shared_memory.h"
-#include "base/string16.h"
-#include "content/common/content_export.h"
-#include "ipc/ipc_channel_proxy.h"
-
-class FilePath;
-
-namespace content {
-class ChildProcessHostDelegate;
-}
-
-// Provides common functionality for hosting a child process and processing IPC
-// messages between the host and the child process. Users are responsible
-// for the actual launching and terminating of the child processes.
-class CONTENT_EXPORT ChildProcessHost : public IPC::Channel::Listener,
-                                        public IPC::Message::Sender {
- public:
-  // These flags may be passed to GetChildPath in order to alter its behavior,
-  // causing it to return a child path more suited to a specific task.
-  enum {
-    // No special behavior requested.
-    CHILD_NORMAL = 0,
-
-#if defined(OS_LINUX)
-    // Indicates that the child execed after forking may be execced from
-    // /proc/self/exe rather than using the "real" app path. This prevents
-    // autoupdate from confusing us if it changes the file out from under us.
-    // You will generally want to set this on Linux, except when there is an
-    // override to the command line (for example, we're forking a renderer in
-    // gdb). In this case, you'd use GetChildPath to get the real executable
-    // file name, and then prepend the GDB command to the command line.
-    CHILD_ALLOW_SELF = 1 << 0,
-#elif defined(OS_MACOSX)
-
-    // Requests that the child run in a process that does not have the
-    // PIE (position-independent executable) bit set, effectively disabling
-    // ASLR. For process types that need to allocate a large contiguous
-    // region, ASLR may not leave a large enough "hole" for the purpose. This
-    // option should be used sparingly, and only when absolutely necessary.
-    // This option is currently incompatible with CHILD_ALLOW_HEAP_EXECUTION.
-    CHILD_NO_PIE = 1 << 1,
-
-    // Requests that the child run in a process that does not protect the
-    // heap against execution. Normally, heap pages may be made executable
-    // with mprotect, so this mode should be used sparingly. It is intended
-    // for processes that may host plug-ins that expect an executable heap
-    // without having to call mprotect. This option is currently incompatible
-    // with CHILD_NO_PIE.
-    CHILD_ALLOW_HEAP_EXECUTION = 1 << 2,
-#endif
-  };
-
-  virtual ~ChildProcessHost();
-
-  // Returns the pathname to be used for a child process.  If a subprocess
-  // pathname was specified on the command line, that will be used.  Otherwise,
-  // the default child process pathname will be returned.  On most platforms,
-  // this will be the same as the currently-executing process.
-  //
-  // The |flags| argument accepts one or more flags such as CHILD_ALLOW_SELF
-  // and CHILD_ALLOW_HEAP_EXECUTION as defined above. Pass only CHILD_NORMAL
-  // if none of these special behaviors are required.
-  //
-  // On failure, returns an empty FilePath.
-  static FilePath GetChildPath(int flags);
-
-  explicit ChildProcessHost(content::ChildProcessHostDelegate* delegate);
-
-  // IPC::Message::Sender implementation.
-  virtual bool Send(IPC::Message* message) OVERRIDE;
-
-  // Adds an IPC message filter.  A reference will be kept to the filter.
-  void AddFilter(IPC::ChannelProxy::MessageFilter* filter);
-
-  // Public and static for reuse by RenderMessageFilter.
-  static void AllocateSharedMemory(
-      uint32 buffer_size, base::ProcessHandle child_process,
-      base::SharedMemoryHandle* handle);
-
-  // Generates a unique channel name for a child process.
-  // The "instance" pointer value is baked into the channel id.
-  static std::string GenerateRandomChannelID(void* instance);
-
-  // Returns a unique ID to identify a child process. On construction, this
-  // function will be used to generate the id_, but it is also used to generate
-  // IDs for the RenderProcessHost, which doesn't inherit from us, and whose IDs
-  // must be unique for all child processes.
-  //
-  // This function is threadsafe since RenderProcessHost is on the UI thread,
-  // but normally this will be used on the IO thread.
-  static int GenerateChildProcessUniqueId();
-
-  // Send the shutdown message to the child process.
-  // Does not check if CanShutdown is true.
-  void ForceShutdown();
-
-  // Creates the IPC channel.  Returns true iff it succeeded.
-  bool CreateChannel();
-
-  bool opening_channel() { return opening_channel_; }
-  const std::string& channel_id() { return channel_id_; }
-  IPC::Channel* channel() { return channel_.get(); }
-
- private:
-  // IPC::Channel::Listener methods:
-  virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
-  virtual void OnChannelConnected(int32 peer_pid) OVERRIDE;
-  virtual void OnChannelError() OVERRIDE;
-
-  // Message handlers:
-  void OnShutdownRequest();
-  void OnAllocateSharedMemory(uint32 buffer_size,
-                              base::SharedMemoryHandle* handle);
-
-  content::ChildProcessHostDelegate* delegate_;
-  base::ProcessHandle peer_handle_;
-  bool opening_channel_;  // True while we're waiting the channel to be opened.
-  scoped_ptr<IPC::Channel> channel_;
-  std::string channel_id_;
-
-  // Holds all the IPC message filters.  Since this object lives on the IO
-  // thread, we don't have a IPC::ChannelProxy and so we manage filters
-  // manually.
-  std::vector<scoped_refptr<IPC::ChannelProxy::MessageFilter> > filters_;
-
-  DISALLOW_COPY_AND_ASSIGN(ChildProcessHost);
-};
-
-#endif  // CONTENT_COMMON_CHILD_PROCESS_HOST_H_