Bug 1941910 - Use dummy ProcessWatcher on Android and iOS. r=ipc-reviewers,nika

Differential Revision: https://phabricator.services.mozilla.com/D234433

ipc/chromium/moz.build

@@ -68,6 +68,14 @@ if CONFIG["TARGET_KERNEL"] != "WINNT":
         "src/base/thread_local_posix.cc",
         "src/base/waitable_event_posix.cc",
         "src/chrome/common/ipc_channel_posix.cc",
+    ]
+
+    if CONFIG["TARGET_OS"] in ("Android", "iOS"):
+        UNIFIED_SOURCES += [
+            "src/chrome/common/process_watcher_dummy.cc",
+        ]
+    else:
+        UNIFIED_SOURCES += [
             "src/chrome/common/process_watcher_posix_sigchld.cc",
         ]
 

ipc/chromium/src/chrome/common/process_watcher_dummy.cc

@@ -0,0 +1,9 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "chrome/common/process_watcher.h"
+
+void ProcessWatcher::EnsureProcessTerminated(base::ProcessHandle, bool) {}

ipc/chromium/src/chrome/common/process_watcher_posix_sigchld.cc

@@ -30,6 +30,12 @@
 #  include "mozilla/ipc/ForkServiceChild.h"
 #endif
 
+// Just to make sure the moz.build is doing the right things with
+// TARGET_OS and/or OS_TARGET:
+#if defined(MOZ_WIDGET_ANDROID) || defined(MOZ_WIDGET_UIKIT)
+#  error Unsupported OS
+#endif
+
 #if !defined(XP_DARWIN)
 // Linux, {Free,Net,Open}BSD, and Solaris; but not macOS, yet.
 #  define HAVE_PIPE2 1