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diff --git a/dom/ipc/PreallocatedProcessManager.h b/dom/ipc/PreallocatedProcessManager.h
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+/* -*- 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/. */
+
+#ifndef mozilla_PreallocatedProcessManager_h
+#define mozilla_PreallocatedProcessManager_h
+
+#include "base/basictypes.h"
+#include "nsCOMPtr.h"
+#include "nsIObserver.h"
+
+namespace mozilla {
+namespace dom {
+class ContentParent;
+} // namespace dom
+
+/**
+ * This class manages a ContentParent that it starts up ahead of any particular
+ * need.  You can then call Take() to get this process and use it.  Since we
+ * already started it up, it should be ready for use faster than if you'd
+ * created the process when you needed it.
+ *
+ * This class watches the dom.ipc.processPrelaunch.enabled pref.  If it changes
+ * from false to true, it preallocates a process.  If it changes from true to
+ * false, it kills the preallocated process, if any.
+ *
+ * We don't expect this pref to flip between true and false in production, but
+ * flipping the pref is important for tests.
+ *
+ * The static methods here are implemented by forwarding calls on to a
+ * PreallocatedProcessManagerImpl singleton class, so if you add a new static
+ * method here, you'll need to write a corresponding public method on the
+ * singleton.
+ */
+class PreallocatedProcessManager final
+{
+  typedef mozilla::dom::ContentParent ContentParent;
+
+public:
+  /**
+   * Create a process after a delay.  We wait for a period of time (specified
+   * by the dom.ipc.processPrelaunch.delayMs pref), then wait for this process
+   * to go idle, then allocate the new process.
+   *
+   * If the dom.ipc.processPrelaunch.enabled pref is false, or if we already
+   * have a preallocated process, this function does nothing.
+   */
+  static void AllocateAfterDelay();
+
+  /**
+   * Create a process once this process goes idle.
+   *
+   * If the dom.ipc.processPrelaunch.enabled pref is false, or if we already
+   * have a preallocated process, this function does nothing.
+   */
+  static void AllocateOnIdle();
+
+  /**
+   * Create a process right now.
+   *
+   * If the dom.ipc.processPrelaunch.enabled pref is false, or if we already
+   * have a preallocated process, this function does nothing.
+   */
+  static void AllocateNow();
+
+  /**
+   * Take the preallocated process, if we have one.  If we don't have one, this
+   * returns null.
+   *
+   * If you call Take() twice in a row, the second call is guaranteed to return
+   * null.
+   *
+   * After you Take() the preallocated process, you need to call one of the
+   * Allocate* functions (or change the dom.ipc.processPrelaunch pref from
+   * false to true) before we'll create a new process.
+   */
+  static already_AddRefed<ContentParent> Take();
+
+private:
+  PreallocatedProcessManager();
+  DISALLOW_EVIL_CONSTRUCTORS(PreallocatedProcessManager);
+};
+
+} // namespace mozilla
+
+#endif // defined mozilla_PreallocatedProcessManager_h