Adding sync integration tests to official build artifacts

Following the steps done in https://codereview.chromium.org/323163003/

Not sure how to test this, any guidance?

I want the sync_integration_tests binary to be stored in
official Chrome build gs:// drops just like
browser_tests and other test binaries already are. Then
I can set up automation to approve new releases of Sync
server.

BUG=411389

Review URL: https://codereview.chromium.org/545103003

Cr-Original-Commit-Position: refs/heads/master@{#293775}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: de3a5e8b35ad6b7452acb0502b27fb77b37e9a7c

all.gyp

@@ -1126,6 +1126,7 @@
               'dependencies': [
                 '../base/base.gyp:base_unittests',
                 '../chrome/chrome.gyp:browser_tests',
+		'../chrome/chrome.gyp:sync_integration_tests', 
                 '../chrome/chrome.gyp:crash_service',
                 '../chrome/chrome.gyp:gcapi_dll',
                 '../chrome/chrome.gyp:pack_policy_templates',