Switch Pepper Linux to use shared USB<->native key conversion table.

remoting/host/desktop_session_agent.cc

Index: remoting/host/desktop_session_agent.cc
diff --git a/remoting/host/desktop_session_agent.cc b/remoting/host/desktop_session_agent.cc
index 6f0996e31981a451fccf3bb0ffa28ce7c7ff30d9..cd476779402093d43dda868baa3a7a8d1a1168af 100644
--- a/remoting/host/desktop_session_agent.cc
+++ b/remoting/host/desktop_session_agent.cc
@@ -437,7 +437,8 @@ void DesktopSessionAgent::OnInjectKeyEvent(
 
   // Ignore unknown keycodes.
   if (event.has_usb_keycode() &&
-      UsbKeycodeToNativeKeycode(event.usb_keycode()) == kInvalidKeycode) {
+      (UsbKeycodeToNativeKeycode(event.usb_keycode()) ==
+           InvalidNativeKeycode())) {
     LOG(ERROR) << "KeyEvent: unknown USB keycode: "
                << std::hex << event.usb_keycode() << std::dec;
     return;