[Telemetry] Add capability for values to reference external files.

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..200dcaaa6e0bd716caf21299211e97df6a7ddf6d 100644
--- a/tools/telemetry/telemetry/results/json_output_formatter.py
+++ b/tools/telemetry/telemetry/results/json_output_formatter.py
@@ -2,21 +2,27 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import errno
+import itertools
 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, dirname=os.curdir):
   """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 is also responsible for outputting trace files, if they
+  exist.
 
   Args:
-    page_test_results: a PageTestResults object
-    benchmark_metadata: a benchmark.BenchmarkMetadata object
+    page_test_results: A PageTestResults object
+    benchmark_metadata: A benchmark.BenchmarkMetadata object
+    dirname: The dir that the results are being output to.
   """
   result_dict = {
     'format_version': '0.2',
@@ -25,11 +31,39 @@ def ResultsAsDict(page_test_results, benchmark_metadata):
                        page_test_results.all_summary_values],
     'per_page_values': [v.AsDict() for v in
                         page_test_results.all_page_specific_values],
-    'pages': {p.id: p.AsDict() for p in _GetAllPages(page_test_results)}
+    'pages': {p.id: p.AsDict() for p in _GetAllPages(page_test_results)},
   }
 
+  #TODO(eakuefner): Refactor this to support more than HTML results.
+  files = OutputFiles(page_test_results, dirname, '.html')
+
+  if files:
+    result_dict['files'] = files
+
   return result_dict
 
+def OutputFiles(page_test_results, dirname, extension):
+  file_handles = _AllFileHandles(page_test_results)
+
+  trace_dirname = dirname + '/trace_files'
+  try:
+    if file_handles:
+      os.makedirs(trace_dirname)
+  except OSError as exc:
+    if exc.errno == errno.EEXIST and os.path.isdir(trace_dirname):
+      pass
+    else:
+      raise
+
+  return file_handle.OutputFiles(file_handles, trace_dirname + '/', extension)
+
+def _AllFileHandles(page_test_results):
+  values = itertools.chain(page_test_results.all_summary_values,
+                           page_test_results.all_page_specific_values)
+  return [fh for fh in map(lambda value: value.GetAssociatedFileHandle(),
+                           values)
+          if fh is not None]
+
 def _GetAllPages(page_test_results):
   pages = set(page_run.page for page_run in
               page_test_results.all_page_runs)