Move some basic early process init into Service Manager

services/service_manager/embedder/main_delegate.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SERVICES_SERVICE_MANAGER_EMBEDDER_MAIN_DELEGATE_H_
+#define SERVICES_SERVICE_MANAGER_EMBEDDER_MAIN_DELEGATE_H_
+
+#include "services/service_manager/embedder/service_manager_embedder_export.h"
+
+namespace base {
+namespace mac {
+class ScopedNSAutoreleasePool;
+}
+}
+
+namespace service_manager {
+
+// An interface which must be implemented by Service Manager embedders to
+// control basic process initialization and shutdown, as well as early branching
+// to run specific types of subprocesses.
+class MainDelegate {
+ public:
+  // Extra parameters passed to MainDelegate::Initialize.
+  struct InitializeParams {
+#if defined(OS_MACOSX)
+    // The outermost autorelease pool, allocated by internal service manager
+    // logic. This is guaranteed to live throughout the extent of Run().
+    base::mac::ScopedNSAutoreleasePool* autorelease_pool = nullptr;
+#endif
+  };
+
+  virtual ~MainDelegate() {}
+
+  // Perform early process initialization. Returns -1 if successful, or the exit
+  // code with which the process should be terminated due to initialization
+  // failure.
+  virtual int Initialize(const InitializeParams& params) = 0;
+
+  // Runs the main process logic. Called exactly once, and only after a
+  // successful call to Initialize(). Returns the exit code to use when
+  // terminating the process after Run() (and then ShutDown()) completes.
+  virtual int Run() = 0;
+
+  // Called after Run() returns, before exiting the process.
+  virtual void ShutDown() = 0;
+};
+
+}  // namespace service_manager
+
+#endif  // SERVICES_SERVICE_MANAGER_EMBEDDER_MAIN_DELEGATE_H_