Do not delete temporary directory if user specified it manually.

This prevents user from accidentally specifying a directory that contains
files that the user wants to keep.

BUG=webrtc:7608
NOTRY=True

Review-Url: https://codereview.webrtc.org/2876803002
Cr-Commit-Position: refs/heads/master@{#18096}
diff --git a/webrtc/examples/androidtests/gradle_project_test.py b/webrtc/examples/androidtests/gradle_project_test.py
index 07ae570..9a0621b 100644
--- a/webrtc/examples/androidtests/gradle_project_test.py
+++ b/webrtc/examples/androidtests/gradle_project_test.py
@@ -67,7 +67,9 @@
         '--use-gradle-process-resources', '--split-projects'])
     _RunCommand([GRADLEW_BIN, 'assembleDebug'], project_dir)
   finally:
-    shutil.rmtree(project_dir, True)
+    # Do not delete temporary directory if user specified it manually.
+    if not args.project_dir:
+      shutil.rmtree(project_dir, True)
 
 
 if __name__ == '__main__':