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

tools/perf/metrics/memory.py

Index: tools/perf/metrics/memory.py
diff --git a/tools/perf/metrics/memory.py b/tools/perf/metrics/memory.py
index 70b2ccff928fe81306e7339efcddc720ade139c2..4f026bf3967f44771b647a383cefb66f9b0eb3f0 100644
--- a/tools/perf/metrics/memory.py
+++ b/tools/perf/metrics/memory.py
@@ -7,6 +7,7 @@ import sys
 from metrics import Metric
 from telemetry.value import histogram
 from telemetry.value import histogram_util
+from telemetry.value import improvement_direction
 from telemetry.value import scalar
 
 
@@ -17,13 +18,15 @@ _HISTOGRAMS = [
         'type': histogram_util.RENDERER_HISTOGRAM,
         'description': 'Total external memory fragmentation after each GC in '
                        'percent.',
+        'improvement_direction': improvement_direction.DOWN,
     },
     {
         'name': 'V8.MemoryHeapSampleTotalCommitted', 'units': 'kb',
         'display_name': 'V8_MemoryHeapSampleTotalCommitted',
         'type': histogram_util.RENDERER_HISTOGRAM,
         'description': 'The total size of committed memory used by V8 after '
-                       'each GC in KB.'
+                       'each GC in KB.',
+        'improvement_direction': improvement_direction.DOWN,
     },
     {
         'name': 'V8.MemoryHeapSampleTotalUsed', 'units': 'kb',
@@ -31,21 +34,25 @@ _HISTOGRAMS = [
         'type': histogram_util.RENDERER_HISTOGRAM,
         'description': 'The total size of live memory used by V8 after each '
                        'GC in KB.',
+        'improvement_direction': improvement_direction.DOWN,
     },
     {
         'name': 'V8.MemoryHeapSampleMaximumCommitted', 'units': 'kb',
         'display_name': 'V8_MemoryHeapSampleMaximumCommitted',
-        'type': histogram_util.RENDERER_HISTOGRAM
+        'type': histogram_util.RENDERER_HISTOGRAM,
+        'improvement_direction': improvement_direction.DOWN,
     },
     {
         'name': 'Memory.RendererUsed', 'units': 'kb',
         'display_name': 'Memory_RendererUsed',
-        'type': histogram_util.RENDERER_HISTOGRAM
+        'type': histogram_util.RENDERER_HISTOGRAM,
+        'improvement_direction': improvement_direction.DOWN,
     },
     {
         'name': 'Memory.BrowserUsed', 'units': 'kb',
         'display_name': 'Memory_BrowserUsed',
-        'type': histogram_util.BROWSER_HISTOGRAM
+        'type': histogram_util.BROWSER_HISTOGRAM,
+        'improvement_direction': improvement_direction.DOWN,
     },
 ]
 
@@ -121,7 +128,8 @@ class MemoryMetric(Metric):
       results.AddValue(histogram.HistogramValue(
           results.current_page, h['display_name'], h['units'],
           raw_value_json=self._histogram_delta[h['name']], important=False,
-          description=h.get('description')))
+          description=h.get('description'),
+          improvement_direction=h['improvement_direction']))
     self._memory_stats = self._browser.memory_stats
     if not self._memory_stats['Browser']:
       return
@@ -135,11 +143,13 @@ class MemoryMetric(Metric):
           results.current_page,
           'commit_charge.' + (trace_name or 'commit_charge'),
           'kb', commit_charge_difference, important=False,
-          description='System commit charge (committed memory pages).'))
+          description='System commit charge (committed memory pages).',
+          improvement_direction=improvement_direction.DOWN))
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'processes.' + (trace_name or 'processes'),
         'count', self._memory_stats['ProcessCount'], important=False,
-        description='Number of processes used by Chrome.'))
+        description='Number of processes used by Chrome.',
+        improvement_direction=improvement_direction.DOWN))
 
 
 def AddResultsForProcesses(results, memory_stats, chart_trace_name='final',
@@ -193,7 +203,8 @@ def AddResultsForProcesses(results, memory_stats, chart_trace_name='final',
           chart_name = current_trace
         results.AddValue(scalar.ScalarValue(
             results.current_page, '%s.%s' % (chart_name, current_trace), 'kb',
-            sum(values) / 1024, important=False, description=description))
+            sum(values) / 1024, important=False, description=description,
+            improvement_direction=improvement_direction.DOWN))
 
     AddResult('VM', 'vm_%s_size' % chart_trace_name,
               'Virtual Memory Size (address space allocated).')