[Telemetry][CodeHealth] Make unittests with fake platforms use fakes.FakePlatform

telemetry/telemetry/testing/fakes/__init__.py

 # Copyright 2015 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.
 
 """Provides fakes for several of Telemetry's internal objects.
 
 These allow code like story_runner and Benchmark to be run and tested
 without compiling or starting a browser. Class names prepended with an
 underscore are intended to be implementation details, and should not
 be subclassed; however, some, like _FakeBrowser, have public APIs that
 may need to be called in tests.
 """
+import tempfile
+
 from telemetry.internal.backends.chrome_inspector import websocket
 from telemetry.internal.browser import browser_options
+from telemetry.internal.image_processing import video
 from telemetry.internal.platform import system_info
 from telemetry.page import shared_page_state
 from telemetry.util import image_util
 from telemetry.testing.internal import fake_gpu_info
 from types import ModuleType
 
 
 # Classes and functions which are intended to be part of the public
 # fakes API.
 
+class FakePlatformBackend(object):
+  def __init__(self):
+    self.platform = FakePlatform()
+
+  def DidStartBrowser(self, _, _2):

[nednguyen, 2017/05/16 17:39:25]

nits: our style is keep the parameter the same & use "del param_1, param_2  #
unused"

[rnephew (Reviews Here), 2017/05/16 17:56:28]

Done.

+    pass
+
+  def WillCloseBrowser(self, _, _2):
+    pass
+
+
 class FakePlatform(object):
   def __init__(self):
     self._network_controller = None
     self._tracing_controller = None
     self._has_battor = False
     self._os_name = 'FakeOS'
+    self.device = 'fake_device'
+    self._is_video_capture_running = False
+
+  def StartVideoCapture(self, _):
+    self._is_video_capture_running = True
+
+  def StopVideoCapture(self):
+    self._is_video_capture_running = False
+    return video.Video(tempfile.NamedTemporaryFile())
+
+  @property
+  def is_video_capture_running(self):
+    return self._is_video_capture_running
 
   @property
   def is_host_platform(self):
     raise NotImplementedError
 
   @property
   def network_controller(self):
     if self._network_controller is None:
       self._network_controller = _FakeNetworkController()
     return  self._network_controller
@@ skipping 506 matching lines @@
     self._elapsed_time = time
 
   def __del__(self):
     self.Restore()
 
   def Restore(self):
     if self._module:
       self._module.time = self._actual_time
       self._module = None
       self._actual_time = None
-