C++11: Use type aliases instead of typedefs

snapshot/mac/mach_o_image_symbol_table_reader.h

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 48 matching lines @@
   // and there aren’t expected to be very many of those that performance would
   // become a problem. std::map is also guaranteed to be part of the standard
   // library, which isn’t the case for std::unordered_map, which requires the
   // C++11 library. In reality, std::unordered_map does not appear to provide
   // a performance advantage. It appears that the memory copies currently done
   // by TaskMemory::Read() have substantially more impact on symbol table
   // operations.
   //
   // This is public so that the type is available to
   // MachOImageSymbolTableReaderInitializer.
-  typedef std::map<std::string, SymbolInformation> SymbolInformationMap;
+  using SymbolInformationMap = std::map<std::string, SymbolInformation>;
 
   MachOImageSymbolTableReader();
   ~MachOImageSymbolTableReader();
 
   //! \brief Reads the symbol table from another process.
   //!
   //! This method must only be called once on an object. This method must be
   //! called successfully before any other method in this class may be called.
   //!
   //! \param[in] process_reader The reader for the remote process.
@@ skipping 46 matching lines @@
  private:
   SymbolInformationMap external_defined_symbols_;
   InitializationStateDcheck initialized_;
 
   DISALLOW_COPY_AND_ASSIGN(MachOImageSymbolTableReader);
 };
 
 }  // namespace crashpad
 
 #endif  // CRASHPAD_SNAPSHOT_MAC_MACH_O_IMAGE_SYMBOL_TABLE_READER_H_