[Telemetry] Reorganize everything.

tools/telemetry/telemetry/core/extension_dict.py

 # Copyright (c) 2012 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.
-
-from telemetry import extension_to_load
+from telemetry.core import extension_to_load
 
 class ExtensionDict(object):
   """Dictionary of ExtensionPage instances, with extension_id as key"""
 
   def __init__(self, extension_dict_backend):
     self._extension_dict_backend = extension_dict_backend
 
   def __getitem__(self, load_extension):
     """Given an ExtensionToLoad instance, returns the corresponding
     ExtensionPage instance."""
     if not isinstance(load_extension, extension_to_load.ExtensionToLoad):
       raise Exception("Input param must be of type ExtensionToLoad")
     return self._extension_dict_backend.__getitem__(
         load_extension.extension_id())
 
   def __contains__(self, load_extension):
     """Checks if this ExtensionToLoad instance has been loaded"""
     if not isinstance(load_extension, extension_to_load.ExtensionToLoad):
       raise Exception("Input param must be of type ExtensionToLoad")
     return self._extension_dict_backend.__contains__(
         load_extension.extension_id())