HLE: Move SessionRequestHandler from Service:: to Kernel::

Most of the code that works with this is or will be in the kernel, so
it's a more appropriate place for it to be.

src/core/hle/kernel/hle_ipc.h

@@ -0,0 +1,52 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <vector>
+#include "core/hle/kernel/kernel.h"
+
+namespace Kernel {
+
+class ServerSession;
+
+/**
+ * Interface implemented by HLE Session handlers.
+ * This can be provided to a ServerSession in order to hook into several relevant events
+ * (such as a new connection or a SyncRequest) so they can be implemented in the emulator.
+ */
+class SessionRequestHandler {
+public:
+    /**
+     * Handles a sync request from the emulated application.
+     * @param server_session The ServerSession that was triggered for this sync request,
+     * it should be used to differentiate which client (As in ClientSession) we're answering to.
+     * TODO(Subv): Use a wrapper structure to hold all the information relevant to
+     * this request (ServerSession, Originator thread, Translated command buffer, etc).
+     * @returns ResultCode the result code of the translate operation.
+     */
+    virtual void HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) = 0;
+
+    /**
+     * Signals that a client has just connected to this HLE handler and keeps the
+     * associated ServerSession alive for the duration of the connection.
+     * @param server_session Owning pointer to the ServerSession associated with the connection.
+     */
+    void ClientConnected(Kernel::SharedPtr<Kernel::ServerSession> server_session);
+
+    /**
+     * Signals that a client has just disconnected from this HLE handler and releases the
+     * associated ServerSession.
+     * @param server_session ServerSession associated with the connection.
+     */
+    void ClientDisconnected(Kernel::SharedPtr<Kernel::ServerSession> server_session);
+
+protected:
+    /// List of sessions that are connected to this handler.
+    /// A ServerSession whose server endpoint is an HLE implementation is kept alive by this list
+    // for the duration of the connection.
+    std::vector<Kernel::SharedPtr<Kernel::ServerSession>> connected_sessions;
+};
+
+} // namespace Kernel