Add manifest output to the bot_update api.

scripts/slave/recipe_modules/bot_update/example.py

Index: scripts/slave/recipe_modules/bot_update/example.py
diff --git a/scripts/slave/recipe_modules/bot_update/example.py b/scripts/slave/recipe_modules/bot_update/example.py
index 4491b77272f00f7030bda2e6eddc1981032e4e19..d891a475fe35e52943abddb0c7cba3fc0e2a9502 100644
--- a/scripts/slave/recipe_modules/bot_update/example.py
+++ b/scripts/slave/recipe_modules/bot_update/example.py
@@ -18,11 +18,13 @@ def GenSteps(api):
   soln.url = 'svn://svn.chromium.org/chrome/trunk/src'
   api.gclient.c = src_cfg
   force = True if api.properties.get('force') else False
+  output_manifest = api.properties.get('output_manifest', False)
   with_branch_heads = api.properties.get('with_branch_heads', False)
   refs = api.properties.get('refs', [])
   oauth2 = api.properties.get('oauth2', False)
   api.bot_update.ensure_checkout(force=force,
                                  with_branch_heads=with_branch_heads,
+                                 output_manifest=output_manifest,
                                  refs=refs, patch_oauth2=oauth2)
 
 
@@ -38,6 +40,12 @@ def GenTests(api):
       slavename='totallyaslave-m1',
       with_branch_heads=True,
   )
+  yield api.test('basic_output_manifest') + api.properties(
+      mastername='chromium.linux',
+      buildername='Linux Builder',
+      slavename='totallyaslave-m1',
+      output_manifest=True,
+  )
   yield api.test('tryjob') + api.properties(
       mastername='tryserver.chromium.linux',
       buildername='linux_rel',