Convert most Chromium presubmit files to use new multiple-tryserver-compatible protocol

native_client_sdk/PRESUBMIT.py

Index: native_client_sdk/PRESUBMIT.py
diff --git a/native_client_sdk/PRESUBMIT.py b/native_client_sdk/PRESUBMIT.py
index d219be389a31b37252b855ae024ada053b1d61a7..ac9fd612e53faa5d210ea44a2b7d8cf40b24a5b0 100644
--- a/native_client_sdk/PRESUBMIT.py
+++ b/native_client_sdk/PRESUBMIT.py
@@ -38,12 +38,14 @@ def CheckChangeOnCommit(input_api, output_api):
   return CommonChecks(input_api, output_api)
 
 
-def GetPreferredTrySlaves(project, change):
-  return [
-    'linux_nacl_sdk',
-    'linux_nacl_sdk_build',
-    'win_nacl_sdk',
-    'win_nacl_sdk_build',
-    'mac_nacl_sdk',
-    'mac_nacl_sdk_build'
-  ]
+def GetPreferredTryMasters(project, change):
+  return {
+    'tryserver.chromium': {
+      'linux_nacl_sdk': set(['defaulttests']),
+      'linux_nacl_sdk_build': set(['defaulttests']),
+      'win_nacl_sdk': set(['defaulttests']),
+      'win_nacl_sdk_build': set(['defaulttests']),
+      'mac_nacl_sdk': set(['defaulttests']),
+      'mac_nacl_sdk_build': set(['defaulttests']),
+    }
+  }