[ServiceWorker] Added size deltas and total size computation for QuotaM.

content/public/browser/service_worker_usage_info.cc

 // Copyright 2014 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/public/browser/service_worker_usage_info.h"
 
 namespace content {
 
 ServiceWorkerUsageInfo::ServiceWorkerUsageInfo(const GURL& origin,
                                                const std::vector<GURL>& scopes)
-    : origin(origin), scopes(scopes) {
+    : origin(origin), scopes(scopes), total_size_bytes(0) {
 }
 
 ServiceWorkerUsageInfo::ServiceWorkerUsageInfo(const GURL& origin)
-    : origin(origin) {
+    : origin(origin), total_size_bytes(0) {
 }
 
-ServiceWorkerUsageInfo::ServiceWorkerUsageInfo() {
+ServiceWorkerUsageInfo::ServiceWorkerUsageInfo() : total_size_bytes(0) {
 }
 
 ServiceWorkerUsageInfo::~ServiceWorkerUsageInfo() {
 }
 
 }  // namespace content