Reland of Migrate DeviceUtils.ReadFile to adb_wrapper (try 3)

tools/telemetry/telemetry/core/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 re
 import shutil
 import subprocess
 import tempfile
@@ skipping 329 matching lines @@
   def StartMonitoringPower(self, browser):
     self._power_monitor.StartMonitoringPower(browser)
 
   def StopMonitoringPower(self):
     return self._power_monitor.StopMonitoringPower()
 
   def GetFileContents(self, fname):
     if not self._can_access_protected_file_contents:
       logging.warning('%s cannot be retrieved on non-rooted device.' % fname)
       return ''
-    return '\n'.join(self._device.ReadFile(fname, as_root=True))
+    return self._device.ReadFile(fname, as_root=True)
 
   def GetPsOutput(self, columns, pid=None):
     assert columns == ['pid', 'name'] or columns == ['pid'], \
         'Only know how to return pid and name. Requested: ' + columns
     command = 'ps'
     if pid:
       command += ' -p %d' % pid
     ps = self._device.RunShellCommand(command)[1:]
     output = []
     for line in ps:
@@ skipping 279 matching lines @@
         if 'cpu_affinity' in dir(process):
           process.cpu_affinity([0])      # New versions of psutil.
         elif 'set_cpu_affinity' in dir(process):
           process.set_cpu_affinity([0])  # Older versions.
         else:
           logging.warn(
               'Cannot set CPU affinity due to stale psutil version: %s',
               '.'.join(str(x) for x in psutil.version_info))
     except (psutil.NoSuchProcess, psutil.AccessDenied):
       logging.warn('Failed to set adb process CPU affinity')