LibCore+LibIPC+Everywhere: Return Stream::LocalSocket from LocalServer

This change unfortunately cannot be atomically made without a single
commit changing everything.

Most of the important changes are in LibIPC/Connection.cpp,
LibIPC/ServerConnection.cpp and LibCore/LocalServer.cpp.

The notable changes are:
- IPCCompiler now generates the decode and decode_message functions such
  that they take a Core::Stream::LocalSocket instead of the socket fd.
- IPC::Decoder now uses the receive_fd method of LocalSocket instead of
  doing system calls directly on the fd.
- IPC::ConnectionBase and related classes now use the Stream API
  functions.
- IPC::ServerConnection no longer constructs the socket itself; instead,
  a convenience macro, IPC_CLIENT_CONNECTION, is used in place of
  C_OBJECT and will generate a static try_create factory function for
  the ServerConnection subclass. The subclass is now responsible for
  passing the socket constructed in this function to its
  ServerConnection base; the socket is passed as the first argument to
  the constructor (as a NonnullOwnPtr<Core::Stream::LocalServer>) before
  any other arguments.
- The functionality regarding taking over sockets from SystemServer has
  been moved to LibIPC/SystemServerTakeover.cpp. The Core::LocalSocket
  implementation of this functionality hasn't been deleted due to my
  intention of removing this class in the near future and to reduce
  noise on this (already quite noisy) PR.

1 files changed, 4 insertions, 3 deletions

diff --git a/Userland/Applets/Audio/main.cpp b/Userland/Applets/Audio/main.cpp
index 40dfb5bbd5..8ce65dbe30 100644
--- a/Userland/Applets/Audio/main.cpp
+++ b/Userland/Applets/Audio/main.cpp
@@ -41,14 +41,15 @@ public:
             { 0, TRY(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/audio-volume-zero.png")) },
             { 0, TRY(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/audio-volume-muted.png")) }
         };
-        NonnullRefPtr<AudioWidget> audio_widget = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) AudioWidget(move(volume_level_bitmaps))));
+        auto audio_client = TRY(Audio::ClientConnection::try_create());
+        NonnullRefPtr<AudioWidget> audio_widget = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) AudioWidget(move(audio_client), move(volume_level_bitmaps))));
         TRY(audio_widget->try_initialize_graphical_elements());
         return audio_widget;
     }
 
 private:
-    AudioWidget(Vector<VolumeBitmapPair, 5> volume_level_bitmaps)
-        : m_audio_client(Audio::ClientConnection::construct())
+    AudioWidget(NonnullRefPtr<Audio::ClientConnection> audio_client, Vector<VolumeBitmapPair, 5> volume_level_bitmaps)
+        : m_audio_client(move(audio_client))
         , m_volume_level_bitmaps(move(volume_level_bitmaps))
         , m_show_percent(Config::read_bool("AudioApplet", "Applet", "ShowPercent", false))
     {