Stop to use contextmanager for goma.build_with_goma

scripts/slave/recipe_modules/chromium/api.py

Index: scripts/slave/recipe_modules/chromium/api.py
diff --git a/scripts/slave/recipe_modules/chromium/api.py b/scripts/slave/recipe_modules/chromium/api.py
index eed50545ce7a30f2a7fb17f8f88afcacc2c52f31..f69e543c6337986401b36e91d3985987911faddc 100644
--- a/scripts/slave/recipe_modules/chromium/api.py
+++ b/scripts/slave/recipe_modules/chromium/api.py
@@ -291,25 +291,24 @@ class ChromiumApi(recipe_api.RecipeApi):
 
       kwargs.pop('env', {})
 
-      # TODO(tikuta): Set disable_local_fallback option appropriately.
       if use_goma_module:
         with self.m.goma.build_with_goma(
             env=goma_env,
             ninja_log_outdir=target_output_dir,
             ninja_log_compiler=self.c.compile_py.compiler or 'goma',
             ninja_log_command=command,
-            allow_build_without_goma=allow_build_without_goma):
-          if 'GOMA_DISABLED' in goma_env:
-            self.m.goma.remove_j_flag(command)
-            ninja_env['GOMA_DISABLED'] = 'true'
-            if self.m.platform.is_win:
-              self.m.python('update windows env',
-                            script=self.package_repo_resource(
-                                'scripts', 'slave', 'update_windows_env.py'),
-                            args=['--envfile-dir', str(target_output_dir)],
-                            env=goma_env)
+            allow_build_without_goma=allow_build_without_goma) as (
+                env_update, ninja_command):
+          ninja_env.update(env_update)
+          if self.m.platform.is_win and 'GOMA_DISABLED' in env_update:
+            goma_env.update(env_update)
+            self.m.python('update windows env',
+                          script=self.package_repo_resource(
+                              'scripts', 'slave', 'update_windows_env.py'),
+                          args=['--envfile-dir', str(target_output_dir)],
+                          env=goma_env)
           self.m.step(name or 'compile with ninja',
-                      command,
+                      ninja_command,
                       env=ninja_env,
                       **kwargs)
       else: