Telemetry (memory benchmark): Add histogram Memory.RendererUsed.

tools/perf/perf_tools/memory_benchmark.py

Index: tools/perf/perf_tools/memory_benchmark.py
diff --git a/tools/perf/perf_tools/memory_benchmark.py b/tools/perf/perf_tools/memory_benchmark.py
index 683f5f080ba7c7cfdfbc1c0836d337ea14487dfb..5cbd0bbbda8b8a2c6363ab43c6370c0d30d67254 100644
--- a/tools/perf/perf_tools/memory_benchmark.py
+++ b/tools/perf/perf_tools/memory_benchmark.py
@@ -6,7 +6,8 @@ from telemetry import multi_page_benchmark
 MEMORY_HISTOGRAMS = [
     {'name': 'V8.MemoryExternalFragmentationTotal', 'units': 'percent'},
     {'name': 'V8.MemoryHeapSampleTotalCommitted', 'units': 'kb'},
-    {'name': 'V8.MemoryHeapSampleTotalUsed', 'units': 'kb'}]
+    {'name': 'V8.MemoryHeapSampleTotalUsed', 'units': 'kb'},
+    {'name': 'Memory.RendererUsed', 'units': 'kb'}]
 
 class MemoryBenchmark(multi_page_benchmark.MultiPageBenchmark):
   def __init__(self):
@@ -21,6 +22,7 @@ class MemoryBenchmark(multi_page_benchmark.MultiPageBenchmark):
     # customizing, so that we get the same generic histograms produced for all
     # pages.
     options.AppendExtraBrowserArg('--disable-histogram-customizer')
+    options.AppendExtraBrowserArg('--memory-metrics')
 
   def CanRunForPage(self, page):
     return hasattr(page, 'stress_memory')