Raise an error if cryptohome-path fails.

BUG=375717
TEST=trybot, manual
NOTRY=True

Review URL: https://codereview.chromium.org/297823002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272028 0039d316-1c4b-4281-b951-d872f2087c98

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

@@ -48,8 +48,8 @@ class CrOSBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
     # Note that we also perform this copy locally to ensure that
     # the owner of the extensions is set to chronos.
     for e in extensions_to_load:
-      output = cri.RunCmdOnDevice(['mktemp', '-d', '/tmp/extension_XXXXX'])
-      extension_dir = output[0].rstrip()
+      extension_dir = cri.RunCmdOnDevice(
+          ['mktemp', '-d', '/tmp/extension_XXXXX'])[0].rstrip()
       cri.PushFile(e.path, extension_dir)
       cri.Chown(extension_dir)
       e.local_path = os.path.join(extension_dir, os.path.basename(e.path))

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

@@ -196,7 +196,7 @@ class CrOSInterface(object):
       if "Connection timed out" in stderr:
         raise OSError('Machine wasn\'t responding to ssh: %s' %
                       stderr)
-      raise OSError('Unepected error: %s' % stderr)
+      raise OSError('Unexpected error: %s' % stderr)
     exists = stdout == '1\n'
     logging.debug("FileExistsOnDevice(<text>, %s)->%s" % (file_name, exists))
     return exists
@@ -401,8 +401,11 @@ class CrOSInterface(object):
 
   def CryptohomePath(self, user):
     """Returns the cryptohome mount point for |user|."""
-    return self.RunCmdOnDevice(
-        ['cryptohome-path', 'user', "'%s'" % user])[0].strip()
+    stdout, stderr = self.RunCmdOnDevice(
+        ['cryptohome-path', 'user', "'%s'" % user])
+    if stderr != '':
+      raise OSError('cryptohome-path failed: %s' % stderr)
+    return stdout.rstrip()
 
   def IsCryptohomeMounted(self, username, is_guest):
     """Returns True iff |user|'s cryptohome is mounted."""