Fix potential null pointer dereference.

src/google_breakpad/processor/minidump.h

 // Copyright (c) 2010 Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 883 matching lines @@
   // Print the contents of this mapping.
   void Print();
 
  private:
   // These objects are managed by MinidumpLinuxMapsList.
   friend class MinidumpLinuxMapsList;
 
   // This caller owns the pointer.
   explicit MinidumpLinuxMaps(Minidump *minidump);
 
-  // Read data about a single mapping from /proc/self/maps and load the data
-  // into this object. The input vector is in the same format as a line from
-  // /proc/self/maps.
-
   // The memory region struct that this class wraps.
   MappedMemoryRegion region_;
 
   DISALLOW_COPY_AND_ASSIGN(MinidumpLinuxMaps);
 };
 
 // MinidumpLinuxMapsList corresponds to the Linux-exclusive MD_LINUX_MAPS
 // stream, which contains the contents of /prod/self/maps, which contains
 // the mapped memory regions and their access permissions.
 class MinidumpLinuxMapsList : public MinidumpStream {
@@ skipping 202 matching lines @@
   // construction or after a failed Read(); true following a successful
   // Read().
   bool                      valid_;
 };
 
 
 }  // namespace google_breakpad
 
 
 #endif  // GOOGLE_BREAKPAD_PROCESSOR_MINIDUMP_H__