[CT] Add desktop device when running run_benchmark

ct/go/worker_scripts/run_chromium_perf_swarming/main.go

 // run_chromium_perf_swarming is an application that is meant to be run on
 // a swarming slave. It runs the specified benchmark over CT's webpage
 // archives and uploads results to chromeperf.appspot.com
 package main
 
 import (
         "flag"
         "fmt"
         "io/ioutil"
         "os"
@@ skipping 125 matching lines @@
                 // Documentation is here: http://www.chromium.org/developers/speed-infra/performance-dashboard/sending-data-to-the-performance-dashboard
                 "--output-format=chartjson",
                 // Upload traces.
                 "--upload-results",
                 "--upload-bucket=output",
         }
 
         // Need to capture output for all benchmarks.
         outputDirArgValue := filepath.Join(localOutputDir, pagesetName)
         args = append(args, "--output-dir="+outputDirArgValue)
-        // Figure out which browser should be used.
+        // Figure out which browser and device should be used.
         if *targetPlatform == util.PLATFORM_ANDROID {
                 if err := util.InstallChromeAPK(chromiumBuildName); err != nil {
                         return fmt.Errorf("Error while installing APK: %s", err)
                 }
                 args = append(args, "--browser=android-chromium")
         } else {
                 args = append(args, "--browser=exact", "--browser-executable="+chromiumBinary)
+                args = append(args, "--device=desktop")
         }
         // Split benchmark args if not empty and append to args.
         if *benchmarkExtraArgs != "" {
                 args = append(args, strings.Fields(*benchmarkExtraArgs)...)
         }
         // Add the number of times to repeat.
         args = append(args, fmt.Sprintf("--page-repeat=%d", *repeatBenchmark))
         // Add browserArgs if not empty to args.
         if browserExtraArgs != "" {
                 args = append(args, "--extra-browser-args="+browserExtraArgs)
         }
         // Set the PYTHONPATH to the pagesets and the telemetry dirs.
         env := []string{
                 fmt.Sprintf("PYTHONPATH=%s:$PYTHONPATH", *telemetryBinariesDir),
                 "DISPLAY=:0",
         }
         timeoutSecs := 2 * 60 // 2 mins timeout
         if err := util.ExecuteCmd("python", args, env, time.Duration(timeoutSecs)*time.Second, nil, nil); err != nil {
                 glog.Errorf("Run benchmark command failed with: %s", err)
         }
         return nil
 }