[devil] Clarify DeviceUtils.Install{,SplitApk} failure on missing APK.

devil/devil/android/device_utils.py

Index: devil/devil/android/device_utils.py
diff --git a/devil/devil/android/device_utils.py b/devil/devil/android/device_utils.py
index 427fbb50bade1aa30270b82832b5a40ee3419bc5..36a5317316dba029ce1e77f70423c9f1f7fc994e 100644
--- a/devil/devil/android/device_utils.py
+++ b/devil/devil/android/device_utils.py
@@ -16,6 +16,7 @@ import logging
 import multiprocessing
 import os
 import posixpath
+import pprint
 import re
 import shutil
 import stat
@@ -701,6 +702,12 @@ class DeviceUtils(object):
       if len(all_apks) == 1:
         logger.warning('split-select did not select any from %s', split_apks)
 
+    missing_apks = [apk for apk in all_apks if not os.path.exists(apk)]
+    if missing_apks:
+      raise device_errors.CommandFailedError(
+          'Attempted to install non-existent apks: %s'
+              % pprint.pformat(missing_apks))
+
     package_name = base_apk.GetPackageName()
     device_apk_paths = self._GetApplicationPathsInternal(package_name)