Add ability to only upload a single Chromium build and check for patch existence

ct/go/master_scripts/run_chromium_perf_on_workers/main.go

Index: ct/go/master_scripts/run_chromium_perf_on_workers/main.go
diff --git a/ct/go/master_scripts/run_chromium_perf_on_workers/main.go b/ct/go/master_scripts/run_chromium_perf_on_workers/main.go
index 4bd170960a16432c2fac8d9f4b9d0795fc896a0e..b400ec74adfcf56b23c35abdc0c3b39bf69e6712 100644
--- a/ct/go/master_scripts/run_chromium_perf_on_workers/main.go
+++ b/ct/go/master_scripts/run_chromium_perf_on_workers/main.go
@@ -165,7 +165,7 @@ func main() {
 	benchmarkPatchLink = util.GS_HTTP_LINK + filepath.Join(util.GSBucketName, remoteOutputDir, benchmarkPatchName)
 
 	// Create the two required chromium builds (with patch and without the patch).
-	chromiumHash, skiaHash, err := util.CreateChromiumBuild(*runID, *targetPlatform, "", "", true)
+	chromiumHash, skiaHash, err := util.CreateChromiumBuild(*runID, *targetPlatform, "", "", true, false)
 	if err != nil {
 		glog.Errorf("Could not create chromium build: %s", err)
 		return