[telemetry_mini] Add UserStory class

experimental/telemetry_mini/telemetry_mini.py

 #!/usr/bin/env python
 # Copyright 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This is intended to be a very trimmed down, single-file, hackable, and easy
 # to understand version of Telemetry. It's able to run simple user stories on
 # Android, grab traces, and extract metrics from them. May be useful to
 # diagnose issues with Chrome, reproduce regressions or prototype new user
 # stories.
@@ skipping 372 matching lines @@
     # System Chrome app cannot be (un)installed, so we enable/disable instead.
     logging.warning('Enabling %s', self.PACKAGE_NAME)
     self.device.RunShellCommand('pm', 'enable', self.PACKAGE_NAME)
 
   def Uninstall(self):
     # System Chrome app cannot be (un)installed, so we enable/disable instead.
     logging.warning('Disabling %s', self.PACKAGE_NAME)
     self.device.RunShellCommand('pm', 'disable', self.PACKAGE_NAME)
 
 
+class UserStory(object):
+  def __init__(self, browser):
+    self.device = browser.device
+    self.browser = browser
+
+  def GetExtraStoryApps(self):
+    """Sequence of AndroidApp's, other than the browser, used in the story."""
+    return ()
+
+  def EnsureExtraStoryAppsClosed(self):
+    running_processes = self.device.ProcessStatus()
+    for app in self.GetExtraStoryApps():
+      if app.PACKAGE_NAME in running_processes:
+        app.ForceStop()
+
+  def Run(self, browser_flags, trace_config, trace_file):
+    with self.browser.Session(browser_flags, trace_config):
+      self.EnsureExtraStoryAppsClosed()
+      try:
+        self.RunStorySteps()
+        self.browser.CollectTrace(trace_file)
+      except Exception as exc:
+        # Helps to pin point in the logs the moment where the story failed,
+        # before any of the finally blocks get to be executed.
+        logging.error('Aborting story due to %s.', type(exc).__name__)
+        raise
+      finally:
+        self.EnsureExtraStoryAppsClosed()
+
+  def RunStorySteps(self):
+    """Subclasses should override this method to implement the story.
+
+    The steps must:
+    - at some point cause the browser to be launched, and
+    - make sure the browser remains alive when done (even if backgrounded).
+    """
+    raise NotImplementedError
+
+
 def ReadProcessMetrics(trace_file):
   """Return a list of {"name": process_name, metric: value} dicts."""
   with open(trace_file) as f:
     trace = json.load(f)
 
   processes = collections.defaultdict(dict)
   for event in trace['traceEvents']:
     if event['ph'] == 'v':
       # Extract any metrics you may need from the trace.
       value = event['args']['dumps']['allocators'][
           'java_heap/allocated_objects']['attrs']['size']
       assert value['units'] == 'bytes'
       processes[event['pid']]['java_heap'] = int(value['value'], 16)
     elif event['ph'] == 'M' and event['name'] == 'process_name':
       processes[event['pid']]['name'] = event['args']['name']
 
   return processes.values()