Define measurements as a tuple of name and spec.

mojo/tools/data/benchmarks

 # This file contains a list of Mojo benchmarks. For description of the file
 # format, see `mojo_benchmark --help`.
 
 benchmarks = [
   {
     'name': 'dart init',
     'app': 'https://core.mojoapps.io/dart_traced_application.mojo',
     'duration': 10,
     'measurements': [
-      'time_until/traced_application/initialized',
-      'time_between/traced_application/initialized/traced_application/connected',
+      {
+        'name': 'initialize',
+        'spec': 'time_until/traced_application/initialized'
+      },
+      {
+        'name': 'accept connection',
+        'spec': 'time_between/traced_application/initialized/traced_application/connected',
+      }
     ]
   },
   {
     'name': 'dart init with handler',
     'app': 'https://core.mojoapps.io/dart_handler_running.mojo',
     'duration': 10,
     'measurements': [
-      'time_between/dart_handler_running/connecting/traced_application/initialized',
+      {
+        'name': 'initialize',
+        'spec': 'time_between/dart_handler_running/connecting/traced_application/initialized',
+      }
     ]
   },
   {
     'name': 'cpp init',
     'app': 'https://core.mojoapps.io/trace_me.mojo',
     'duration': 10,
     'measurements': [
-      'time_until/trace_me/initialized',
-      'time_between/trace_me/initialized/trace_me/connected',
+      {
+        'name': 'initialize',
+        'spec': 'time_until/trace_me/initialized',
+      },
+      {
+        'name': 'accept connection',
+        'spec': 'time_between/trace_me/initialized/trace_me/connected',
+      }
     ],
     'shell-args': [
       '--args-for=https://core.mojoapps.io/trace_me.mojo --early-tracing',
     ]
   },
 ]