[results_processor] Provide file URL to generated outputs

This feature got missing when moving output formatting from Telemetry
to Results Processor.

Bug: 1017904
Change-Id: I36258576b5fc72ab7a0093dc74b7882cfd5a1d19
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879936
Auto-Submit: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709598}

tools/perf/core/results_processor/formatters/csv_output.py

@@ -54,3 +54,5 @@ def ProcessHistogramDicts(histogram_dicts, options):
 
   with open(output_file, 'w') as output_stream:
     _WriteCsv(csv_dicts, output_stream)
+
+  return output_file

tools/perf/core/results_processor/formatters/histograms_output.py

@@ -30,3 +30,5 @@ def ProcessHistogramDicts(histogram_dicts, options):
 
   with open(output_file, 'w') as output_stream:
     json.dump(histogram_dicts, output_stream)
+
+  return output_file

tools/perf/core/results_processor/formatters/html_output.py

@@ -20,3 +20,4 @@ def ProcessHistogramDicts(histogram_dicts, options):
   with codecs.open(output_file, mode='r+', encoding='utf-8') as output_stream:
     vulcanize_histograms_viewer.VulcanizeAndRenderHistogramsViewer(
         histogram_dicts, output_stream, options.reset_results)
+  return output_file

tools/perf/core/results_processor/formatters/json3_output.py

@@ -23,8 +23,10 @@ OUTPUT_FILENAME = 'test-results.json'
 def ProcessIntermediateResults(test_results, options):
   """Process intermediate results and write output in output_dir."""
   results = Convert(test_results, options.output_dir)
-  with open(os.path.join(options.output_dir, OUTPUT_FILENAME), 'w') as f:
+  output_file = os.path.join(options.output_dir, OUTPUT_FILENAME)
+  with open(output_file, 'w') as f:
     json.dump(results, f, sort_keys=True, indent=4, separators=(',', ': '))
+  return output_file
 
 
 def Convert(test_results, base_dir):

tools/perf/core/results_processor/processor.py

@@ -8,6 +8,8 @@ Provides functions to process intermediate results, and the entry point to
 the standalone version of Results Processor.
 """
 
+from __future__ import print_function
+
 import datetime
 import json
 import logging
@@ -84,9 +86,10 @@ def ProcessResults(options):
     logging.info('Processing format: %s', output_format)
     formatter = formatters.FORMATTERS[output_format]
     if output_format in FORMATS_WITH_METRICS:
-      formatter.ProcessHistogramDicts(histogram_dicts, options)
+      output_file = formatter.ProcessHistogramDicts(histogram_dicts, options)
     else:
-      formatter.ProcessIntermediateResults(test_results, options)
+      output_file = formatter.ProcessIntermediateResults(test_results, options)
+    print('View results at file://', output_file, sep='')
 
   return GenerateExitCode(test_results)