Pick up histogram output file if we're outputting histograms

HistogramSet has a different default output filename when using Telemetry; we
need to account for this in run_telemetry_benchmark_as_googletest so that that
script can find the histogram output if present.

Bug: 744736
Change-Id: I1fec4a2d86e7e0a9700bc0b44160b78f0484d866
Reviewed-on: https://chromium-review.googlesource.com/683780Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#504486}

testing/scripts/run_telemetry_benchmark_as_googletest.py

@@ -54,9 +54,9 @@ def main():
   for output_format in args.output_format:
     rest_args.append('--output-format=' + output_format)
 
-  rc, chartresults, json_test_results = run_benchmark(args, rest_args)
+  rc, perf_results, json_test_results = run_benchmark(args, rest_args)
 
-  if chartresults:
+  if perf_results:
     if args.isolated_script_test_perf_output:
       filename = args.isolated_script_test_perf_output
     elif args.isolated_script_test_chartjson_output:
@@ -65,8 +65,8 @@ def main():
       filename = None
 
     if filename is not None:
-      with open(filename, 'w') as chartjson_output_file:
-        json.dump(chartresults, chartjson_output_file)
+      with open(filename, 'w') as perf_results_output_file:
+        json.dump(perf_results, perf_results_output_file)
 
   json.dump(json_test_results, args.isolated_script_test_output)
 
@@ -81,8 +81,9 @@ def run_benchmark(args, rest_args):
   tempfile_dir = tempfile.mkdtemp('telemetry')
   valid = True
   num_failures = 0
+  histogram_results_present = 'histograms' in args.output_format
   chartjson_results_present = 'chartjson' in args.output_format
-  chartresults = None
+  perf_results = None
   json_test_results = None
 
   results = None
@@ -99,10 +100,16 @@ def run_benchmark(args, rest_args):
     # If we have also output chartjson read it in and return it.
     # results-chart.json is the file name output by telemetry when the
     # chartjson output format is included
-    if chartjson_results_present:
-      chart_tempfile_name = os.path.join(tempfile_dir, 'results-chart.json')
-      with open(chart_tempfile_name) as f:
-        chartresults = json.load(f)
+    if histogram_results_present:
+      tempfile_name = os.path.join(tempfile_dir, 'histograms.json')
+    elif chartjson_results_present:
+      tempfile_name = os.path.join(tempfile_dir, 'results-chart.json')
+    else:
+      tempfile_name = None
+
+    if tempfile_name is not None:
+      with open(tempfile_name) as f:
+        perf_results = json.load(f)
 
     # test-results.json is the file name output by telemetry when the
     # json-test-results format is included
@@ -125,7 +132,7 @@ def run_benchmark(args, rest_args):
     if rc == 0:
       rc = 1  # Signal an abnormal exit.
 
-  return rc, chartresults, json_test_results
+  return rc, perf_results, json_test_results
 
 
 # This is not really a "script test" so does not need to manually add