[telemetry] Sort imports in Telemetry and its dependents.

tools/telemetry/telemetry/core/backends/browser_backend.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.core.backends import app_backend
+from telemetry.core import platform
+from telemetry.core.platform import profiling_controller_backend
+from telemetry.core import web_contents
 from telemetry import decorators
-from telemetry.core import platform
-from telemetry.core import web_contents
-from telemetry.core.backends import app_backend
-from telemetry.core.platform import profiling_controller_backend
 
 
 class ExtensionsNotSupportedException(Exception):
   pass
 
 
 class BrowserBackend(app_backend.AppBackend):
   """A base class for browser backends."""
 
   def __init__(self, platform_backend, supports_extensions, browser_options,
@@ skipping 74 matching lines @@
     return self.IsBrowserRunning()
 
   def GetStandardOutput(self):
     raise NotImplementedError()
 
   def GetStackTrace(self):
     raise NotImplementedError()
 
   def GetSystemInfo(self):
     raise NotImplementedError()