Fix the units for the draw_properties benchmark.

tools/perf/unit-info.json

 {
   "_description" : "This file contains info about our performance test units, used by the perf dashboard (http://chromeperf.appspot.com).",
 
   "%": {
     "improvement_direction": "down",
     "why": "Percent CPU usage. Used by cpu metric."
   },
   "bit/s": {
     "improvement_direction": "down",
     "why": "Bitrate."
@@ skipping 132 matching lines @@
     "improvement_direction": "up",
     "why": "Used in alloy-perf-test/cts%/passed."
   },
   "points": {
     "improvement_direction": "up",
     "why": "Synonym for score, used in ChromeOS touchpad tests."
   },
   "ports": {
     "improvement_direction": "down"
   },
+  "reduction%": {
+    "improvement_direction": "up",
+    "why": "Used in draw_property measurement to indicate relative improvement."
+  },
   "relocs": {
     "improvement_direction": "down"
   },
   "runs/ms": {
     "improvement_direction": "up",
     "why": "Higher runs/ms implies faster execution."
   },
   "runs/s": {
     "improvement_direction": "up",
     "why": "Used in dromaeo. Higher runs/s implies faster execution."
@@ skipping 32 matching lines @@
   },
   "vsyncs": {
     "improvement_direction": "down",
     "why": "Used in smoothness benchmarks. Number of vsyncs to generate a frame, never < 1.0"
   },
   "idle%": {
     "improvement_direction": "up",
     "why": "Percentage of work done in idle time."
   }
 }