Mojo: Implement MojoUnmapBuffer().

mojo/system/mapping_table.h

+// Copyright 2014 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 MOJO_SYSTEM_MAPPING_TABLE_H_
+#define MOJO_SYSTEM_MAPPING_TABLE_H_
+
+#include <stdint.h>
+
+#include <vector>
+
+#include "base/containers/hash_tables.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "mojo/public/c/system/core.h"
+#include "mojo/system/system_impl_export.h"
+
+namespace mojo {
+namespace system {
+
+class CoreImpl;
+class RawSharedBufferMapping;
+
+// Test-only function (defined/used in embedder/test_embedder.cc). Declared here
+// so it can be friended.
+namespace internal {
+bool ShutdownCheckNoLeaks(CoreImpl*);
+}
+
+// This class provides the (global) table of memory mappings (owned by
+// |CoreImpl|), which maps mapping base addresses to
+// |RawSharedBuffer::Mapping|s.
+//
+// This class is NOT thread-safe; locking is left to |CoreImpl|.
+class MOJO_SYSTEM_IMPL_EXPORT MappingTable {
+ public:
+  MappingTable();
+  ~MappingTable();
+
+  // Tries to add a mapping. (Takes ownership of the mapping in all cases; on
+  // failure, it will be destroyed.)
+  MojoResult AddMapping(scoped_ptr<RawSharedBufferMapping> mapping);
+  MojoResult RemoveMapping(void* address);
+
+ private:
+  friend bool internal::ShutdownCheckNoLeaks(CoreImpl*);
+
+  typedef base::hash_map<uintptr_t, RawSharedBufferMapping*>
+      AddressToMappingMap;
+  AddressToMappingMap address_to_mapping_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(MappingTable);
+};
+
+}  // namespace system
+}  // namespace mojo
+
+#endif  // MOJO_SYSTEM_MAPPING_TABLE_H_