Enable installing test CA on Android & add test for it

telemetry/telemetry/internal/platform/android_platform_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.
 
 import logging
 import os
 import posixpath
 import re
 import subprocess
 import tempfile
@@ skipping 528 matching lines @@
   def IsAppRunning(self, process_name):
     """Determine if the given process is running.
 
     Args:
       process_name: The full package name string of the process.
     """
     return bool(self._device.GetPids(process_name))
 
   @property
   def supports_test_ca(self):
-    # TODO(nednguyen): figure out how to install certificate on Android M
-    # crbug.com/593152
-    # TODO(crbug.com/716084): enable support for test CA
-    # return self._device.build_version_sdk <= version_codes.LOLLIPOP_MR1
-    return False
+    return True
 
   def InstallTestCa(self):
     """Install a randomly generated root CA on the android device.
 
     This allows transparent HTTPS testing with WPR server without need
     to tweak application network stack.
 
     Note: If this method fails with any exception, then RemoveTestCa will be
     automatically called by the network_controller_backend.
     """
@@ skipping 278 matching lines @@
   for process in psutil.process_iter():
     try:
       if psutil.version_info >= (2, 0):
         if 'adb' in process.name():
           process.cpu_affinity([0])
       else:
         if 'adb' in process.name:
           process.set_cpu_affinity([0])
     except (psutil.NoSuchProcess, psutil.AccessDenied):
       logging.warn('Failed to set adb process CPU affinity')