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

content/common/child_process_host_impl.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_
+#ifndef CONTENT_COMMON_CHILD_PROCESS_HOST_IMPL_H_
+#define CONTENT_COMMON_CHILD_PROCESS_HOST_IMPL_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"
+#include "content/public/common/child_process_host.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 {
+class CONTENT_EXPORT ChildProcessHostImpl : public ChildProcessHost,
+                                            public IPC::Channel::Listener {
  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);
+  virtual ~ChildProcessHostImpl();
 
   // 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(); }
+  // ChildProcessHost implementation
+  virtual bool Send(IPC::Message* message) OVERRIDE;
+  virtual void ForceShutdown() OVERRIDE;
+  virtual std::string CreateChannel() OVERRIDE;
+  virtual bool IsChannelOpening() OVERRIDE;
+  virtual void AddFilter(IPC::ChannelProxy::MessageFilter* filter) OVERRIDE;
+#if defined(OS_POSIX)
+  virtual int TakeClientFileDescriptor() OVERRIDE;
+#endif
 
  private:
+  friend class ChildProcessHost;
+
+  explicit ChildProcessHostImpl(ChildProcessHostDelegate* delegate);
+
   // 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_;
+  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);
+  DISALLOW_COPY_AND_ASSIGN(ChildProcessHostImpl);
 };
 
-#endif  // CONTENT_COMMON_CHILD_PROCESS_HOST_H_
+}  // namespace content
+
+#endif  // CONTENT_COMMON_CHILD_PROCESS_HOST_IMPL_H_