Split out generic portal / pipewire code

It will be reused by the video capture portal / pipewire backend.

Bug: webrtc:13177
Change-Id: Ia1a77f1c6e289149cd8a1d54b550754bf192e62e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/263721
Reviewed-by: Mark Foltz <mfoltz@chromium.org>
Commit-Queue: Alexander Cooper <alcooper@chromium.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Reviewed-by: Salman Malik <salmanmalik@google.com>
Cr-Commit-Position: refs/heads/main@{#38487}

modules/portal/pipewire_utils.cc

@@ -0,0 +1,53 @@
+/*
+ *  Copyright 2022 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "modules/portal/pipewire_utils.h"
+
+#include <pipewire/pipewire.h>
+
+#include "rtc_base/sanitizer.h"
+
+#if defined(WEBRTC_DLOPEN_PIPEWIRE)
+#include "modules/portal/pipewire_stubs.h"
+#endif  // defined(WEBRTC_DLOPEN_PIPEWIRE)
+
+namespace webrtc {
+
+RTC_NO_SANITIZE("cfi-icall")
+bool InitializePipeWire() {
+#if defined(WEBRTC_DLOPEN_PIPEWIRE)
+  static constexpr char kPipeWireLib[] = "libpipewire-0.3.so.0";
+
+  using modules_portal::InitializeStubs;
+  using modules_portal::kModulePipewire;
+
+  modules_portal::StubPathMap paths;
+
+  // Check if the PipeWire library is available.
+  paths[kModulePipewire].push_back(kPipeWireLib);
+
+  static bool result = InitializeStubs(paths);
+
+  return result;
+#else
+  return true;
+#endif  // defined(WEBRTC_DLOPEN_PIPEWIRE)
+}
+
+PipeWireThreadLoopLock::PipeWireThreadLoopLock(pw_thread_loop* loop)
+    : loop_(loop) {
+  pw_thread_loop_lock(loop_);
+}
+
+PipeWireThreadLoopLock::~PipeWireThreadLoopLock() {
+  pw_thread_loop_unlock(loop_);
+}
+
+}  // namespace webrtc