Make `content` target build without unused data members on Linux.

content/renderer/background_sync/background_sync_client_impl.cc

 // Copyright 2015 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.
 
 #include "content/renderer/background_sync/background_sync_client_impl.h"
 
 #include <utility>
 
 #include "content/child/background_sync/background_sync_provider.h"
 #include "content/child/background_sync/background_sync_type_converters.h"
@@ skipping 10 matching lines @@
 void BackgroundSyncClientImpl::Create(
     int64_t service_worker_registration_id,
     mojo::InterfaceRequest<BackgroundSyncServiceClient> request) {
   new BackgroundSyncClientImpl(service_worker_registration_id,
                                std::move(request));
 }
 
 BackgroundSyncClientImpl::~BackgroundSyncClientImpl() {}
 
 BackgroundSyncClientImpl::BackgroundSyncClientImpl(
     int64_t service_worker_registration_id,

[jam, 2016/01/13 16:17:50]

ditto

[mlamouri (slow - plz ping), 2016/01/14 20:13:39]

Done.

     mojo::InterfaceRequest<BackgroundSyncServiceClient> request)
-    : service_worker_registration_id_(service_worker_registration_id),
-      binding_(this, std::move(request)),
-      callback_seq_num_(0) {}
+    : binding_(this, std::move(request)), callback_seq_num_(0) {}
 
 void BackgroundSyncClientImpl::Sync(
     int64_t handle_id,
     content::BackgroundSyncEventLastChance last_chance,
     const SyncCallback& callback) {
   DCHECK(!blink::Platform::current()->mainThread()->isCurrentThread());
   // Get a registration for the given handle_id from the provider. This way
   // the provider knows about the handle and can delete it once Blink releases
   // it.
   // TODO(jkarlin): Change the WebSyncPlatform to support
@@ skipping 45 matching lines @@
       mojo::ConvertTo<scoped_ptr<blink::WebSyncRegistration>>(registration);
 
   blink::WebServiceWorkerContextProxy::LastChanceOption web_last_chance =
       mojo::ConvertTo<blink::WebServiceWorkerContextProxy::LastChanceOption>(
           last_chance);
 
   client->DispatchSyncEvent(*web_registration, web_last_chance, callback);
 }
 
 }  // namespace content