Move RestartUI to CrOSInterface

tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py

Index: tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py b/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
index cc38010ccb1143114b8e595f65ffe315806f8a2e..44e8733c7dc7f56553efeafbd74c81bc31da4700 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
@@ -58,11 +58,8 @@ class CrOSBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
       cri.Chown(extension_dir)
       e.local_path = os.path.join(extension_dir, os.path.basename(e.path))
 
-    self._cri.RunCmdOnDevice(['stop', 'ui'])
-
-    if self.browser_options.clear_enterprise_policy:
-      self._cri.RmRF('/var/lib/whitelist/*')
-      self._cri.RmRF('/home/chronos/Local\ State')
+    self._cri.RestartUI(self.browser_options.clear_enterprise_policy)
+    util.WaitFor(self.IsBrowserRunning, 20)
 
     # Delete test user's cryptohome vault (user data directory).
     if not self.browser_options.dont_override_profile:
@@ -74,9 +71,6 @@ class CrOSBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
                    self.profile_directory)
       cri.Chown(self.profile_directory)
 
-    self._cri.RunCmdOnDevice(['start', 'ui'])
-    util.WaitFor(self.IsBrowserRunning, 20)
-
     self._SetBranchNumber(self._GetChromeVersion())
 
   def GetBrowserStartupArgs(self):
@@ -219,7 +213,8 @@ class CrOSBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
   def Close(self):
     super(CrOSBrowserBackend, self).Close()
 
-    self._RestartUI() # Logs out.
+    if self._cri:
+      self._cri.RestartUI(False) # Logs out.
 
     util.WaitFor(lambda: not self._IsCryptohomeMounted(), 30)
 
@@ -247,14 +242,6 @@ class CrOSBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
   def GetStackTrace(self):
     return 'Cannot get stack trace on CrOS'
 
-  def _RestartUI(self):
-    if self._cri:
-      logging.info('(Re)starting the ui (logs the user out)')
-      if self._cri.IsServiceRunning('ui'):
-        self._cri.RunCmdOnDevice(['restart', 'ui'])
-      else:
-        self._cri.RunCmdOnDevice(['start', 'ui'])
-
   @property
   @decorators.Cache
   def misc_web_contents_backend(self):