[tracing] Improve the memory maps dumper generation format.

base/trace_event/process_memory_totals_dump_provider_unittest.cc

Index: base/trace_event/process_memory_totals_dump_provider_unittest.cc
diff --git a/base/trace_event/process_memory_totals_dump_provider_unittest.cc b/base/trace_event/process_memory_totals_dump_provider_unittest.cc
index c37e612bff04e3aaf013eaad5a63ac5a621c7051..372db63eb5e8344a3d83657c54458a84e7ef7c5b 100644
--- a/base/trace_event/process_memory_totals_dump_provider_unittest.cc
+++ b/base/trace_event/process_memory_totals_dump_provider_unittest.cc
@@ -12,18 +12,18 @@ namespace base {
 namespace trace_event {
 
 TEST(ProcessMemoryTotalsDumpProviderTest, DumpRSS) {
-  auto mdptp = ProcessMemoryTotalsDumpProvider::GetInstance();
+  auto pmtdp = ProcessMemoryTotalsDumpProvider::GetInstance();
   scoped_ptr<ProcessMemoryDump> pmd_before(new ProcessMemoryDump());
   scoped_ptr<ProcessMemoryDump> pmd_after(new ProcessMemoryDump());
 
   ProcessMemoryTotalsDumpProvider::rss_bytes_for_testing = 1024;
-  mdptp->DumpInto(pmd_before.get());
+  pmtdp->DumpInto(pmd_before.get());
 
   // Pretend that the RSS of the process increased of +1M.
   const size_t kAllocSize = 1048576;
   ProcessMemoryTotalsDumpProvider::rss_bytes_for_testing += kAllocSize;
 
-  mdptp->DumpInto(pmd_after.get());
+  pmtdp->DumpInto(pmd_after.get());
 
   ProcessMemoryTotalsDumpProvider::rss_bytes_for_testing = 0;