Revert of Turn ChannelMojo on Mac and Linux

ipc/mojo/ipc_channel_mojo.cc

 // Copyright 2014 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.
 
 #include "ipc/mojo/ipc_channel_mojo.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/lazy_instance.h"
 #include "ipc/ipc_listener.h"
@@ skipping 157 matching lines @@
 
 void ChannelMojo::ChannelInfoDeleter::operator()(
     mojo::embedder::ChannelInfo* ptr) const {
   mojo::embedder::DestroyChannelOnIOThread(ptr);
 }
 
 //------------------------------------------------------------------------------
 
 // static
 bool ChannelMojo::ShouldBeUsed() {
-  // Being conservative, this is currently enabled only on Mac and
-  // Linux even though this should work on all platforms.
-  // TODO(morrita): Turn this on all platform and kill
-  // --enable-renderer-mojo-channel
-#if defined(OS_POSIX) && !defined(OS_ANDROID)
-  return true;
-#else
+  // TODO(morrita): Turn this on for a set of platforms.
   return false;
-#endif
 }
 
 // static
 scoped_ptr<ChannelMojo> ChannelMojo::Create(ChannelMojo::Delegate* delegate,
                                             const ChannelHandle& channel_handle,
                                             Mode mode,
                                             Listener* listener) {
   switch (mode) {
     case Channel::MODE_CLIENT:
       return make_scoped_ptr(
@@ skipping 203 matching lines @@
 
     fdset->CommitAll();
   }
 
   return MOJO_RESULT_OK;
 }
 
 #endif  // defined(OS_POSIX) && !defined(OS_NACL)
 
 }  // namespace IPC