1 files changed, 106 insertions, 0 deletions
diff --git a/hal/WindowIdentifier.h b/hal/WindowIdentifier.h
new file mode 100644
index 0000000000..11c5140f61
--- /dev/null
+++ b/hal/WindowIdentifier.h
@@ -0,0 +1,106 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et ft=cpp : */
+/* 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_hal_WindowIdentifier_h
+#define mozilla_hal_WindowIdentifier_h
+
+#include "mozilla/Types.h"
+#include "nsCOMPtr.h"
+#include "nsTArray.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+namespace hal {
+
+/**
+ * This class serves two purposes.
+ *
+ * First, this class wraps a pointer to a window.
+ *
+ * Second, WindowIdentifier lets us uniquely identify a window across
+ * processes.  A window exposes an ID which is unique only within its
+ * process.  Thus to identify a window, we need to know the ID of the
+ * process which contains it.  But the scope of a process's ID is its
+ * parent; that is, two processes with different parents might have
+ * the same ID.
+ *
+ * So to identify a window, we need its ID plus the IDs of all the
+ * processes in the path from the window's process to the root
+ * process.  We throw in the IDs of the intermediate windows (a
+ * content window is contained in a window at each level of the
+ * process tree) for good measures.
+ *
+ * You can access this list of IDs by calling AsArray().
+ */
+class WindowIdentifier {
+ public:
+  /**
+   * Create an empty WindowIdentifier.  Calls to any of this object's
+   * public methods will assert -- an empty WindowIdentifier may be
+   * used only as a placeholder to code which promises not to touch
+   * the object.
+   */
+  WindowIdentifier();
+
+  /**
+   * Wrap the given window in a WindowIdentifier.  These two
+   * constructors automatically grab the window's ID and append it to
+   * the array of IDs.
+   *
+   * Note that these constructors allow an implicit conversion to a
+   * WindowIdentifier.
+   */
+  explicit WindowIdentifier(nsPIDOMWindowInner* window);
+
+  /**
+   * Create a new WindowIdentifier with the given id array and window.
+   * This automatically grabs the window's ID and appends it to the
+   * array.
+   */
+  WindowIdentifier(nsTArray<uint64_t>&& id, nsPIDOMWindowInner* window);
+
+  /**
+   * Get the list of window and process IDs we contain.
+   */
+  typedef nsTArray<uint64_t> IDArrayType;
+  const IDArrayType& AsArray() const;
+
+  /**
+   * Append the ID of the ContentChild singleton to our array of
+   * window/process IDs.
+   */
+  void AppendProcessID();
+
+  /**
+   * Does this WindowIdentifier identify both a window and the process
+   * containing that window?  If so, we say it has traveled through
+   * IPC.
+   */
+  bool HasTraveledThroughIPC() const;
+
+  /**
+   * Get the window this object wraps.
+   */
+  nsPIDOMWindowInner* GetWindow() const;
+
+ private:
+  /**
+   * Get the ID of the window object we wrap.
+   */
+  uint64_t GetWindowID() const;
+
+  AutoTArray<uint64_t, 3> mID;
+  nsCOMPtr<nsPIDOMWindowInner> mWindow;
+#ifdef DEBUG
+  bool mIsEmpty = false;
+#endif
+};
+
+}  // namespace hal
+}  // namespace mozilla
+
+#endif  // mozilla_hal_WindowIdentifier_h