Add benchmark that tests garbage collector and idle time handler.

tools/perf/benchmarks/memory.py

Index: tools/perf/benchmarks/memory.py
diff --git a/tools/perf/benchmarks/memory.py b/tools/perf/benchmarks/memory.py
index 44b900a9233bd7a0a6af1f33e2e6ca327e0d11f3..521c3e6bbbe3c6da88be4cab8f3849dc72d0fc82 100644
--- a/tools/perf/benchmarks/memory.py
+++ b/tools/perf/benchmarks/memory.py
@@ -41,3 +41,19 @@ class MemoryTop7StressWithSlimmingPaint(benchmark.Benchmark):
   @classmethod
   def Name(cls):
     return 'memory.top_7_stress_slimming_paint'
+
+
+class MemoryIdleMultiTab(benchmark.Benchmark):
+  """Use (recorded) real world web sites and measure memory consumption
+  with many tabs and idle times. """
+  test = memory.Memory
+  page_set = page_sets.IdleMultiTabCasesPageSet
+
+  def CustomizeBrowserOptions(self, options):
+    # This benchmark opens tabs from JavaScript, which does not work
+    # with popup-blocking enabled.
+    options.AppendExtraBrowserArgs(['--disable-popup-blocking'])
+
+  @classmethod
+  def Name(cls):
+    return 'memory.idle_multi_tab'