[Telemetry] Introduce shared_user_story_state for real.

tools/telemetry/telemetry/user_story/shared_user_story_state.py

Index: tools/telemetry/telemetry/user_story/shared_user_story_state.py
diff --git a/tools/telemetry/telemetry/user_story/shared_user_story_state.py b/tools/telemetry/telemetry/user_story/shared_user_story_state.py
new file mode 100644
index 0000000000000000000000000000000000000000..414cd319c49cbe16ae4f25cb1a28eed26c06c480
--- /dev/null
+++ b/tools/telemetry/telemetry/user_story/shared_user_story_state.py
@@ -0,0 +1,63 @@
+# Copyright 2014 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.
+
+
+class SharedUserStoryState(object):
+  """A class that manages the test state across multiple user stories.
+  It's styled on unittest.TestCase for handling test setup & teardown logic.
+
+  """
+
+  def __init__(self, test, options, user_story_set):
+    """ This method is styled on unittest.TestCase.setUpClass.
+    Override to do any action before running user stories that
+    share this same state.
+    Args:
+      test: a page_test.PageTest instance.
+      options: a BrowserFinderOptions instance that contains command line
+        options.
+      user_story_set: a user_story_set.UserStorySet instance.
+    """
+    pass
+
+  @property
+  def platform(self):
+    """ Override to return the platform which user stories that share this same
+    state will be run on.
+    """
+    raise NotImplementedError()
+
+  def WillRunUserStory(self, user_story):
+    """ Override to do any action before running each one of all user stories
+    that share this same state.
+    This method is styled on unittest.TestCase.setUp.
+    """
+    raise NotImplementedError()
+
+  def DidRunUserStory(self, results):
+    """ Override to do any action after running each of all user stories that
+    share this same state.
+    This method is styled on unittest.TestCase.tearDown.
+    """
+    raise NotImplementedError()
+
+  def GetTestExpectationAndSkipValue(self, expectations):
+    """ Return test expectation and skip value instance in case expectation
+    is 'skip'. This is run after WillRunUserStory and before RunUserStory.
+    """
+    raise NotImplementedError()
+
+  def RunUserStory(self, results):
+    """ Override to do any action before running each one of all user stories
+    that share this same state.
+    This method is styled on unittest.TestCase.run.
+    """
+    raise NotImplementedError()
+
+  def TearDownState(self, results):
+    """ Override to do any action after running multiple user stories that
+    share this same state.
+    This method is styled on unittest.TestCase.tearDownClass.
+    """
+    raise NotImplementedError()