Make 'html' telemetry's default output format.

telemetry/telemetry/internal/results/results_options.py

Index: telemetry/telemetry/internal/results/results_options.py
diff --git a/telemetry/telemetry/internal/results/results_options.py b/telemetry/telemetry/internal/results/results_options.py
index 829c4789eaabda13c4a6147814b8a300c79dfb9b..dbe8aa5d1ba14e6cc45ce5d16fdfc4074373a9b4 100644
--- a/telemetry/telemetry/internal/results/results_options.py
+++ b/telemetry/telemetry/internal/results/results_options.py
@@ -38,6 +38,8 @@ _OUTPUT_FORMAT_CHOICES = (
     'none',
     )
 
+_DEFAULT_OUTPUT_FORMAT = 'html'
+
 
 # Filenames to use for given output formats.
 _OUTPUT_FILENAME_LOOKUP = {
@@ -150,7 +152,7 @@ def CreateResults(benchmark_metadata, options,
     options: Contains the options specified in AddResultsOptions.
   """
   if not options.output_formats:
-    options.output_formats = [_OUTPUT_FORMAT_CHOICES[0]]
+    options.output_formats = [_DEFAULT_OUTPUT_FORMAT]
 
   upload_bucket = None
   if options.upload_results: