Have all --output-format produces progress report (in gtest-style).

tools/telemetry/telemetry/results/progress_reporter.py

Index: tools/telemetry/telemetry/results/progress_reporter.py
diff --git a/tools/telemetry/telemetry/timeline/empty_timeline_data_importer.py b/tools/telemetry/telemetry/results/progress_reporter.py
similarity index 23%
copy from tools/telemetry/telemetry/timeline/empty_timeline_data_importer.py
copy to tools/telemetry/telemetry/results/progress_reporter.py
index d400e5952188e450401a87a40eaf1207c7fbfd0c..50ee8d481bda05e87fecaedd8f90725a434493aa 100644
--- a/tools/telemetry/telemetry/timeline/empty_timeline_data_importer.py
+++ b/tools/telemetry/telemetry/results/progress_reporter.py
@@ -2,26 +2,29 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-from telemetry.timeline.timeline_data import TimelineData
 
-class EmptyTimelineDataImporter(object):
-  """Imports empty TimlineData objects."""
-  def __init__(self, model, timeline_data, import_priority=0):
+class ProgressReporter(object):
+  """A class that reports progress of a benchmark to the output stream.
+
+  The reporter produces output whenever a significant event happens
+  during the progress of a benchmark, including (but not limited to):
+  when a page run is started, when a page run finished, any failures
+  during a page run.
+
+  The default implementation outputs nothing.
+  """
+
+  def __init__(self, output_stream):
+    self.output_stream = output_stream
+
+  def WillRunPage(self, page):
+    pass
+
+  def DidAddValue(self, value):
     pass
 
-  @staticmethod
-  def CanImport(timeline_data):
-    if not isinstance(timeline_data, TimelineData):
-      return False
-    event_data = timeline_data.EventData()
-    if isinstance(event_data, list):
-      return len(event_data) == 0
-    elif isinstance(event_data, basestring):
-      return len(event_data) == 0
-    return False
-
-  def ImportEvents(self):
+  def DidAddSuccess(self, page):
     pass
 
-  def FinalizeImport(self):
+  def DidFinishAllTests(self, page_test_results):
     pass