Wait properly for renderer crashes

ipc/ipc_channel_posix.h

Index: ipc/ipc_channel_posix.h
diff --git a/ipc/ipc_channel_posix.h b/ipc/ipc_channel_posix.h
index 06c545cad20fbf8f325ddcec30cdc62ab5cd0edb..e141998b323a733d536b68769aaff42c3d4f3951 100644
--- a/ipc/ipc_channel_posix.h
+++ b/ipc/ipc_channel_posix.h
@@ -57,7 +57,9 @@ class Channel::ChannelImpl : public MessageLoopForIO::Watcher {
   void Close();
   void set_listener(Listener* listener) { listener_ = listener; }
   bool Send(Message* message);
-  int GetClientFileDescriptor() const;
+  int GetClientFileDescriptor();
+  int TakeClientFileDescriptor();
+  void CloseClientFileDescriptor();
   bool AcceptsConnections() const;
   bool HasAcceptedConnection() const;
   bool GetClientEuid(uid_t* client_euid) const;
@@ -109,6 +111,7 @@ class Channel::ChannelImpl : public MessageLoopForIO::Watcher {
   // For a server, the client end of our socketpair() -- the other end of our
   // pipe_ that is passed to the client.
   int client_pipe_;
+  base::Lock client_pipe_lock_;  // Lock that protects |client_pipe_|.
 
 #if defined(IPC_USES_READWRITE)
   // Linux/BSD use a dedicated socketpair() for passing file descriptors.