Added support for improvement_direction to relevant values, which is propogated to chartjson.

tools/perf/metrics/system_memory.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from metrics import memory
 from metrics import Metric
+from telemetry.value import improvement_direction
 from telemetry.value import scalar
 
 
 class SystemMemoryMetric(Metric):
   """SystemMemoryMetric gathers system memory statistic.
 
   This metric collects system memory stats per test.  It reports the difference
   (delta) in system memory starts from the start of the test to the end of it.
   """
 
@@ skipping 40 matching lines @@
       return
     exclude_metrics = exclude_metrics or {}
     memory.AddResultsForProcesses(results, memory_stats,
         metric_trace_name=trace_name, chart_trace_name='delta',
         exclude_metrics=exclude_metrics)
 
     if 'SystemCommitCharge' not in exclude_metrics:
       results.AddValue(scalar.ScalarValue(
           results.current_page,
           'commit_charge_delta.%s' % (trace_name or 'commit_charge'), 'kb',
-          memory_stats['SystemCommitCharge'], important=False))
+          memory_stats['SystemCommitCharge'], important=False,
+          improvement_direction=improvement_direction.DOWN))
 
     if 'ProcessCount' not in exclude_metrics:
       results.AddValue(scalar.ScalarValue(
           results.current_page,
           'processes_delta.%s' % (trace_name or 'processes'), 'count',
-          memory_stats['ProcessCount'], important=False))
+          memory_stats['ProcessCount'], important=False,
+          improvement_direction=improvement_direction.DOWN))
 
 
 def _SubtractMemoryStats(end_memory_stats, start_memory_stats):
   """Computes the difference in memory usage stats.
 
   Each of the two stats arguments is a dict with the following format:
       {'Browser': {metric: value, ...},
        'Renderer': {metric: value, ...},
        'Gpu': {metric: value, ...},
        'ProcessCount': value,
@@ skipping 31 matching lines @@
       memory_stats[process_type] = end_process_memory - start_value
     else:
       for metric in end_process_memory:
         end_value = end_process_memory[metric]
         start_value = start_memory_stats[process_type][metric] or 0
         if 'Peak' in metric:
           memory_stats[process_type][metric] = end_value
         else:
           memory_stats[process_type][metric] = end_value - start_value
   return memory_stats