Add an optional root prefix to Linux dumpers

src/client/linux/microdump_writer/microdump_writer.cc

 // Copyright (c) 2014, 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 332 matching lines @@
     } else {
       dumper_->ElfFileIdentifierForMapping(
           mapping,
           member,
           mapping_id,
           reinterpret_cast<uint8_t*>(&module_identifier));
     }
 
     char file_name[NAME_MAX];
     char file_path[NAME_MAX];
-    LinuxDumper::GetMappingEffectiveNameAndPath(
+    dumper_->GetMappingEffectiveNameAndPath(
         mapping, file_path, sizeof(file_path), file_name, sizeof(file_name));
 
     LogAppend("M ");
     LogAppend(static_cast<uintptr_t>(mapping.start_addr));
     LogAppend(" ");
     LogAppend(mapping.offset);
     LogAppend(" ");
     LogAppend(mapping.size);
     LogAppend(" ");
     LogAppend(module_identifier.data1);
@@ skipping 66 matching lines @@
     dumper.set_crash_signal(context->siginfo.si_signo);
     dumper.set_crash_thread(context->tid);
   }
   MicrodumpWriter writer(context, mappings, microdump_extra_info, &dumper);
   if (!writer.Init())
     return false;
   return writer.Dump();
 }
 
 }  // namespace google_breakpad