Use ChannelMojo between the remoting network and desktop processes.

remoting/host/desktop_session_proxy.h

Index: remoting/host/desktop_session_proxy.h
diff --git a/remoting/host/desktop_session_proxy.h b/remoting/host/desktop_session_proxy.h
index 53ffcad09037ecb394e91329f81994456c5b6c3c..9e678a599311666212fcd8249d210e4d31fd777f 100644
--- a/remoting/host/desktop_session_proxy.h
+++ b/remoting/host/desktop_session_proxy.h
@@ -15,8 +15,8 @@
 #include "base/memory/weak_ptr.h"
 #include "base/process/process.h"
 #include "base/sequenced_task_runner_helpers.h"
+#include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_listener.h"
-#include "ipc/ipc_platform_file.h"
 #include "remoting/host/audio_capturer.h"
 #include "remoting/host/desktop_environment.h"
 #include "remoting/host/screen_resolution.h"
@@ -93,8 +93,7 @@ class DesktopSessionProxy
   void OnChannelError() override;
 
   // Connects to the desktop session agent.
-  bool AttachToDesktop(base::Process desktop_process,
-                       IPC::PlatformFileForTransit desktop_pipe);
+  bool AttachToDesktop(const IPC::ChannelHandle& desktop_pipe);
 
   // Closes the connection to the desktop session agent and cleans up
   // the associated resources.
@@ -204,9 +203,6 @@ class DesktopSessionProxy
   // IPC channel to the desktop session agent.
   std::unique_ptr<IPC::ChannelProxy> desktop_channel_;
 
-  // Handle of the desktop process.
-  base::Process desktop_process_;
-
   int pending_capture_frame_requests_;
 
   // Shared memory buffers by Id. Each buffer is owned by the corresponding