Unbreak memory_benchmark.

tools/telemetry/telemetry/page_benchmark_value.py

Index: tools/telemetry/telemetry/page_benchmark_value.py
diff --git a/tools/telemetry/telemetry/page_benchmark_value.py b/tools/telemetry/telemetry/page_benchmark_value.py
index 0a7c3a9b7100c9d445d03c449f03b0438c021c49..7d355bb7b812495b7b19e73a2aa68e062333ded3 100644
--- a/tools/telemetry/telemetry/page_benchmark_value.py
+++ b/tools/telemetry/telemetry/page_benchmark_value.py
@@ -24,9 +24,9 @@ class PageBenchmarkValue(object):
   @property
   def output_value(self):
     if self.data_type == 'histogram':
-      return GeomMeanAndStdDevFromHistogram(self.value)
+      (mean, _) = GeomMeanAndStdDevFromHistogram(self.value)
+      return mean
     elif isinstance(self.value, list):
       return _Mean(self.value)
     else:
       return self.value
-