Various small fixes for nightly infrastructure tests.

- Change the number of iterations for tests from 1 to 3.
- Increase the timeout for image_chromeos.py, so 'cros flash', which
takes a bit longer than cros_image_to_target.sh did, doesn't get killed
just as its finishing.
- Comment out smoothness.top_25 for now, since it's broken and/or
hanging.

BUG=None
TEST=Successfully ran nightly infrastructure tests with these changes.

Change-Id: I77b663b1910fe12ef927afdf15d88a7c1e82d491
Reviewed-on: https://chrome-internal-review.googlesource.com/157419
Reviewed-by: Yunlian Jiang <yunlian@google.com>
Commit-Queue: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
diff --git a/image_chromeos.py b/image_chromeos.py
index 06328e2..97d1534 100755
--- a/image_chromeos.py
+++ b/image_chromeos.py
@@ -227,7 +227,7 @@
     elif log_level == "average":
       cmd_executer.SetLogLevel("verbose");
     retval = cmd_executer.ChrootRunCommand(options.chromeos_root,
-                                           command, command_timeout=600)
+                                           command, command_timeout=1800)
 
     retries = 0
     while retval != 0 and retries < 2:
@@ -236,7 +236,7 @@
         l.LogOutput("Imaging failed. Retry # %d." % retries)
         l.LogOutput("CMD : %s" % command)
       retval = cmd_executer.ChrootRunCommand(options.chromeos_root,
-                                             command, command_timeout=600)
+                                             command, command_timeout=1800)
 
     if log_level == "average":
       cmd_executer.SetLogLevel(log_level)