Revert of [Android] Don't use a device blacklist if one isn't provided.

build/android/test_runner.py

Index: build/android/test_runner.py
diff --git a/build/android/test_runner.py b/build/android/test_runner.py
index 18b87adec8993a4f364f7972908b2426291ac81b..204c81c0e6bbacd811d5d0af370fac233fbc2745 100755
--- a/build/android/test_runner.py
+++ b/build/android/test_runner.py
@@ -895,10 +895,13 @@
   Returns:
     A list of attached devices.
   """
-  blacklist = (device_blacklist.Blacklist(blacklist_file)
-               if blacklist_file
-               else None)
-
+  if not blacklist_file:
+    # TODO(jbudorick): Remove this once bots pass the blacklist file.
+    blacklist_file = device_blacklist.BLACKLIST_JSON
+    logging.warning('Using default device blacklist %s',
+                    device_blacklist.BLACKLIST_JSON)
+
+  blacklist = device_blacklist.Blacklist(blacklist_file)
   attached_devices = device_utils.DeviceUtils.HealthyDevices(blacklist)
   if test_device:
     test_device = [d for d in attached_devices if d == test_device]