Add MemoryWedge to ios/.

ios/chrome/browser/memory/memory_wedge.h

+// Copyright 2015 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 IOS_CHROME_BROWSER_MEMORY_MEMORY_WEDGE_H_
+#define IOS_CHROME_BROWSER_MEMORY_MEMORY_WEDGE_H_
+
+#include <stdlib.h>
+
+namespace memory_wedge {
+
+// Allocates a chunk of memory that will stay until termination.
+// If wedge_size_in_mb is 0, this is a no-op.
+void AddWedge(size_t wedge_size_in_mb);
+
+// For testing only.
+void RemoveWedgeForTesting();
+
+}  // namespace memory_wedge
+
+#endif  // IOS_CHROME_BROWSER_MEMORY_MEMORY_WEDGE_H_