[NaCl SDK] Use chromium trybots when making changes to native_client_sdk.

Also made change to top-level PRESUBMIT.py to prevent testing default bots when
change is only in native_client_sdk.

BUG=none
[email protected]


Review URL: https://chromiumcodereview.appspot.com/10919303

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@157653 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/native_client_sdk/PRESUBMIT.py b/native_client_sdk/PRESUBMIT.py
index dc0b66c1..c6e613d 100644
--- a/native_client_sdk/PRESUBMIT.py
+++ b/native_client_sdk/PRESUBMIT.py
@@ -33,3 +33,7 @@
 
 def CheckChangeOnCommit(input_api, output_api):
   return CommonChecks(input_api, output_api)
+
+
+def GetPreferredTrySlaves(project, change):
+  return ['linux_nacl_sdk', 'win_nacl_sdk', 'mac_nacl_sdk']