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

ipc/ipc_test_sink.cc

Index: ipc/ipc_test_sink.cc
diff --git a/ipc/ipc_test_sink.cc b/ipc/ipc_test_sink.cc
index e97cffd4448fee541075737514e35a28fd5f2b88..1f76c0484c357521cf029439a3e9898b02602a0e 100644
--- a/ipc/ipc_test_sink.cc
+++ b/ipc/ipc_test_sink.cc
@@ -100,9 +100,9 @@ int TestSink::GetClientFileDescriptor() const {
   return -1;
 }
 
-int TestSink::TakeClientFileDescriptor() {
+base::ScopedFD TestSink::TakeClientFileDescriptor() {
   NOTREACHED();
-  return -1;
+  return base::ScopedFD();
 }
 
 #endif  // defined(OS_POSIX) && !defined(OS_NACL)