Linux: change protobuf default option to allow building

chrome/browser/metrics/proto/study.proto

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 syntax = "proto2";
 
-option optimize_for = LITE_RUNTIME;
-
 package chrome_variations;
 
 // This defines the Protocol Buffer representation of a Chrome Variations study
 // as sent to clients of the Variations server.
 //
 // Next tag: 11
 message Study {
   // The name of the study. Should not contain spaces or special characters.
   // Ex: "my_study"
   required string name = 1;
@@ skipping 102 matching lines @@
     // List of locales that will receive this study. If omitted, the study
     // applies to all locales.
     // Ex: ["en-US", "en-CA"]
     repeated string locale = 6;
   }
 
   // Filtering criteria for this study. A study that is filtered out for a given
   // client is equivalent to that study not being sent at all.
   optional Filter filter = 10;
 }