Stop to use contextmanager for goma.build_with_goma

scripts/slave/recipe_modules/goma/api.py

Index: scripts/slave/recipe_modules/goma/api.py
diff --git a/scripts/slave/recipe_modules/goma/api.py b/scripts/slave/recipe_modules/goma/api.py
index ca0934597f11dcf24806afe7a49d83cd87b0ea80..26b022e7e1b01393fdc893b2aabedb4c8c973df1 100644
--- a/scripts/slave/recipe_modules/goma/api.py
+++ b/scripts/slave/recipe_modules/goma/api.py
@@ -85,7 +85,11 @@ print jobs
 
     Args:
       command: List of command line arg.
+
+    Returns:
+      list(string): Command line args parallel option removed.
     """
+    command = command[:]
     parallel_flag_regexp = re.compile('-j\d*')
     for i in range(len(command)):
       if (isinstance(command[i], str) and
@@ -93,7 +97,8 @@ print jobs
         if command[i] == '-j':
           command.pop(i + 1)
         command.pop(i)
-        return
+        break
+    return command
 
   def ensure_goma(self, canary=False):
     with self.m.step.nest('ensure_goma'):
@@ -336,20 +341,28 @@ print jobs
         This argument should be used with env.
         If starting goma fails, env and ninja_log_command are modified.
 
+    Returns:
+      (env_update, command):
+        Please use env_update and command for ninja in build_with_goma context
+        (e.g. ninja_env.update(env_update)).
+        Appropriate values are set when starting goma fails.
+
     Raises:
       StepFailure or InfraFailure if it fails to build.
     """
     ninja_log_exit_status = 0
-
     if allow_build_without_goma:
       assert(env is not None)
+      assert(ninja_log_command is not None)
+      env = env.copy()
+      ninja_log_command = ninja_log_command[:]
+
       try:
         self.start(env)
       except:
-        env['GOMA_DISABLED'] = 'true'
-        self.remove_j_flag(ninja_log_command)
+        ninja_log_command = self.remove_j_flag(ninja_log_command)
         try:
-          yield
+          yield ({'GOMA_DISABLED':'true'}, ninja_log_command)
         except self.m.step.StepFailure as e: # pragma: no cover
           ninja_log_exit_status = e.retcode
           raise e
@@ -367,7 +380,7 @@ print jobs
       self.start(env)
 
     try:
-      yield
+      yield ({}, ninja_log_command)
     except self.m.step.StepFailure as e: # pragma: no cover
       ninja_log_exit_status = e.retcode
       raise e