Refactoring: Make IPC::Channel::TakeClientFileDescriptor() a ScopedFD.

ipc/ipc_channel_posix.cc

Index: ipc/ipc_channel_posix.cc
diff --git a/ipc/ipc_channel_posix.cc b/ipc/ipc_channel_posix.cc
index 2dfd17e6730cbd305d7a2046def6d90276dea172..c864db23869e123ea2e6700872ddfd41ea866409 100644
--- a/ipc/ipc_channel_posix.cc
+++ b/ipc/ipc_channel_posix.cc
@@ -557,12 +557,12 @@ int ChannelPosix::GetClientFileDescriptor() const {
   return client_pipe_.get();
 }
 
-int ChannelPosix::TakeClientFileDescriptor() {
+base::ScopedFD ChannelPosix::TakeClientFileDescriptor() {
   base::AutoLock lock(client_pipe_lock_);
   if (!client_pipe_.is_valid())
-    return -1;
+    return base::ScopedFD();
   PipeMap::GetInstance()->Remove(pipe_name_);
-  return client_pipe_.release();
+  return client_pipe_.Pass();
 }
 
 void ChannelPosix::CloseClientFileDescriptor() {