[telemetry] Sort imports in Telemetry and its dependents.

tools/perf/benchmarks/memory.py

 # Copyright 2013 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 benchmark
+
 from measurements import memory
 import page_sets
-from telemetry import benchmark
 
 
 @benchmark.Enabled('android')
 class MemoryMobile(benchmark.Benchmark):
   test = memory.Memory
   page_set = page_sets.MobileMemoryPageSet
 
   @classmethod
   def Name(cls):
     return 'memory.mobile_memory'
 
 
 class MemoryTop7Stress(benchmark.Benchmark):
   """Use (recorded) real world web sites and measure memory consumption."""
   test = memory.Memory
   page_set = page_sets.Top7StressPageSet
 
   @classmethod
   def Name(cls):
     return 'memory.top_7_stress'