Stop to use contextmanager for goma.build_with_goma

scripts/slave/recipe_modules/goma/example.py

Index: scripts/slave/recipe_modules/goma/example.py
diff --git a/scripts/slave/recipe_modules/goma/example.py b/scripts/slave/recipe_modules/goma/example.py
index 134b782f3569d6a0942db321f8cd55a2a8ce0e09..93317fc4d4a5a3083432e60fb9585cd813866b86 100644
--- a/scripts/slave/recipe_modules/goma/example.py
+++ b/scripts/slave/recipe_modules/goma/example.py
@@ -26,17 +26,14 @@ def RunSteps(api):
       ninja_log_compiler=api.properties.get('ninja_log_compiler'),
       ninja_log_command=command,
       allow_build_without_goma=allow_build_without_goma,
-      env=env):
-    if 'GOMA_DISABLED' in env:
-      api.goma.remove_j_flag(command)
-      api.step('ninja', command, env=env)
-    else:
-      # build something using goma.
-      api.step('echo goma jobs',
-               ['echo', str(api.goma.recommended_goma_jobs)])
-      api.step('echo goma jobs second',
-               ['echo', str(api.goma.recommended_goma_jobs)])
-      api.step('ninja', command, env=env)
+      env=env) as (env_update, ninja_command):
+    env.update(env_update)
+    # build something using goma.
+    api.step('echo goma jobs',
+             ['echo', str(api.goma.recommended_goma_jobs)])
+    api.step('echo goma jobs second',
+             ['echo', str(api.goma.recommended_goma_jobs)])
+    api.step('ninja', ninja_command, env=env)
 
 def GenTests(api):
   for platform in ('linux', 'win', 'mac'):