Force a Chromium sync on all bots.

Due to https://crbug.com/644722 I had to clean a couple of Android
bots manually. But since the third_part/mockito/src dir is now removed
on those hosts, it's missing until the next sync of Chromium.
Since we have a smartness that avoid syncing in place, we need to force
a new sync for these bots to become healthy again.

TBR=ehmaldonado@webrtc.org

Review URL: https://codereview.webrtc.org/2317373003 .

Cr-Commit-Position: refs/heads/master@{#14134}

sync_chromium.py

@@ -31,7 +31,7 @@ import textwrap
 
 # Bump this whenever the algorithm changes and you need bots/devs to re-sync,
 # ignoring the .last_sync_chromium file
-SCRIPT_VERSION = 7
+SCRIPT_VERSION = 8
 
 ROOT_DIR = os.path.dirname(os.path.abspath(__file__))
 CHROMIUM_NO_HISTORY = 'CHROMIUM_NO_HISTORY'