Bug 1218981 - [mozdevice] Ensure adb.py methods propagate root to other called methods, r=gbrown.

testing/mozbase/mozdevice/mozdevice/adb.py

@@ -1426,18 +1426,19 @@ class ADBDevice(ADBCommand):
             if self._mkdir_p is None or self._mkdir_p:
                 # Use shell_bool to catch the possible
                 # non-zero exitcode if -p is not supported.
-                if self.shell_bool('mkdir -p %s' % path, timeout=timeout):
+                if self.shell_bool('mkdir -p %s' % path, timeout=timeout,
+                                   root=root):
                     self._mkdir_p = True
                     return
             # mkdir -p is not supported. create the parent
             # directories individually.
-            if not self.is_dir(posixpath.dirname(path)):
+            if not self.is_dir(posixpath.dirname(path), root=root):
                 parts = path.split('/')
                 name = "/"
                 for part in parts[:-1]:
                     if part != "":
                         name = posixpath.join(name, part)
-                        if not self.is_dir(name):
+                        if not self.is_dir(name, root=root):
                             # Use shell_output to allow any non-zero
                             # exitcode to raise an ADBError.
                             self.shell_output('mkdir %s' % name,