deploy_chrome: use rsync

BUG=chromium:703259
TEST=deploy_chrome in Simple Chrome, scripts/deploy_chrome_unittest

Change-Id: I906ca999b3eac3e64ec1aaca714d845212ce1362
Reviewed-on: https://chromium-review.googlesource.com/457422
Commit-Ready: Steven Bennetts <stevenjb@chromium.org>
Tested-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
diff --git a/scripts/deploy_chrome.py b/scripts/deploy_chrome.py
index 68f8bc0..fab8791 100644
--- a/scripts/deploy_chrome.py
+++ b/scripts/deploy_chrome.py
@@ -251,7 +251,8 @@
           'Run dev_install on the device to get rsync installed')
     self.device.CopyToDevice('%s/' % os.path.abspath(self.staging_dir),
                              self.options.target_dir,
-                             inplace=True, debug_level=logging.INFO,
+                             mode='rsync', inplace=True,
+                             debug_level=logging.INFO,
                              verbose=self.options.verbose)
 
     for p in self.copy_paths: