[Telemetry] Add file handle & trace value.

tools/telemetry/telemetry/results/json_output_formatter.py

Index: tools/telemetry/telemetry/results/json_output_formatter.py
diff --git a/tools/telemetry/telemetry/results/json_output_formatter.py b/tools/telemetry/telemetry/results/json_output_formatter.py
index bf23ede9b8452d039c828b6e99720b65c74370b9..62d771196735a5bb7a3ab5fa35427da9dc615944 100644
--- a/tools/telemetry/telemetry/results/json_output_formatter.py
+++ b/tools/telemetry/telemetry/results/json_output_formatter.py
@@ -3,20 +3,24 @@
 # found in the LICENSE file.
 
 import json
+import os
 
 from telemetry.results import output_formatter
+from telemetry.util import file_handle
 
-def ResultsAsDict(page_test_results, benchmark_metadata):
+
+def ResultsAsDict(page_test_results, benchmark_metadata, output_dir):
   """Takes PageTestResults to a dict serializable to JSON.
 
   To serialize results as JSON we first convert them to a dict that can be
   serialized by the json module. It also requires a benchmark_metadat object
   for metadata to be integrated into the results (currently the benchmark
-  name).
+  name). This function will also output trace files if they exist.
 
   Args:
     page_test_results: a PageTestResults object
     benchmark_metadata: a benchmark.BenchmarkMetadata object
+    output_dir: the directory that results are being output to.
   """
   result_dict = {
     'format_version': '0.2',
@@ -28,23 +32,41 @@ def ResultsAsDict(page_test_results, benchmark_metadata):
     'pages': {p.id: p.AsDict() for p in _GetAllPages(page_test_results)}
   }
 
+  file_ids_to_paths = _OutputTraceFiles(page_test_results, output_dir)
+  if file_ids_to_paths:
+    result_dict['files'] = file_ids_to_paths
   return result_dict
 
+
+def _OutputTraceFiles(page_test_results, output_dir):
+  file_handles = page_test_results.all_file_handles
+  if not file_handles:
+    return {}
+  trace_dir = os.path.join(output_dir, 'trace_files')
+  if not os.path.isdir(trace_dir):
+    os.makedirs(trace_dir)
+  return file_handle.OutputFiles(file_handles, trace_dir)
+
+
 def _GetAllPages(page_test_results):
   pages = set(page_run.page for page_run in
               page_test_results.all_page_runs)
   return pages
 
+
 class JsonOutputFormatter(output_formatter.OutputFormatter):
-  def __init__(self, output_stream, benchmark_metadata):
+  def __init__(self, output_stream, output_dir, benchmark_metadata):
     super(JsonOutputFormatter, self).__init__(output_stream)
     self._benchmark_metadata = benchmark_metadata
+    self._output_dir = output_dir
 
   @property
   def benchmark_metadata(self):
     return self._benchmark_metadata
 
   def Format(self, page_test_results):
-    json.dump(ResultsAsDict(page_test_results, self.benchmark_metadata),
+    json.dump(
+        ResultsAsDict(
+            page_test_results, self.benchmark_metadata, self._output_dir),
         self.output_stream)
     self.output_stream.write('\n')