Adding a test for measuring memory usage.

tools/perf/perf_tools/multipage_benchmark_runner.py

Index: tools/perf/perf_tools/multipage_benchmark_runner.py
diff --git a/tools/perf/perf_tools/multipage_benchmark_runner.py b/tools/perf/perf_tools/multipage_benchmark_runner.py
index db7861c262e8d70967860b7d7af69fa6e035e1b4..7cf4b4afe876364424ca60c561e373e3815abd99 100755
--- a/tools/perf/perf_tools/multipage_benchmark_runner.py
+++ b/tools/perf/perf_tools/multipage_benchmark_runner.py
@@ -14,6 +14,7 @@ from chrome_remote_control import page_runner
 from chrome_remote_control import page_set
 
 import perf_tools.first_paint_time_benchmark
+import perf_tools.memory_benchmark
 import perf_tools.scrolling_benchmark
 import perf_tools.skpicture_printer
 import perf_tools.texture_upload_benchmark
@@ -22,6 +23,8 @@ import perf_tools.texture_upload_benchmark
 _BENCHMARKS = {
   'first_paint_time_benchmark':
       perf_tools.first_paint_time_benchmark.FirstPaintTimeBenchmark,
+  'memory_benchmark':
+      perf_tools.memory_benchmark.MemoryBenchmark,
   'scrolling_benchmark':
       perf_tools.scrolling_benchmark.ScrollingBenchmark,
   'skpicture_printer':