Make JSONParser a pure interface.

chrome/browser/extensions/webstore_install_helper.cc

 // 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.
 
 #include "chrome/browser/extensions/webstore_install_helper.h"
 
 #include "base/bind.h"
 #include "base/values.h"
 #include "chrome/browser/bitmap_fetcher/bitmap_fetcher.h"
 #include "components/safe_json/safe_json_parser.h"
@@ skipping 13 matching lines @@
 
 WebstoreInstallHelper::WebstoreInstallHelper(
     Delegate* delegate,
     const std::string& id,
     const std::string& manifest,
     const GURL& icon_url,
     net::URLRequestContextGetter* context_getter)
     : delegate_(delegate),
       id_(id),
       manifest_(manifest),
+      json_parser_(nullptr),
       icon_url_(icon_url),
       context_getter_(context_getter),
       icon_decode_complete_(false),
       manifest_parse_complete_(false),
       parse_error_(Delegate::UNKNOWN_ERROR) {
 }
 
 WebstoreInstallHelper::~WebstoreInstallHelper() {}
 
 void WebstoreInstallHelper::Start() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  // No existing |json_parser_| to avoid unbalanced AddRef().
-  CHECK(!json_parser_.get());
-  AddRef();  // Balanced in OnJSONParseSucceeded()/OnJSONParseFailed().
-  // Use base::Unretained so that base::Bind won't AddRef() on us. Otherwise,
-  // we'll have two callbacks holding references to us, only one of which will
-  // ever be called.
-  json_parser_ = new safe_json::SafeJsonParser(
-      manifest_,
-      base::Bind(&WebstoreInstallHelper::OnJSONParseSucceeded,
-                 base::Unretained(this)),
-      base::Bind(&WebstoreInstallHelper::OnJSONParseFailed,
-                 base::Unretained(this)));
+  CHECK(!json_parser_);
+
+  json_parser_ = safe_json::SafeJsonParser::Create(
+      manifest_, base::Bind(&WebstoreInstallHelper::OnJSONParseSucceeded, this),
+      base::Bind(&WebstoreInstallHelper::OnJSONParseFailed, this));
   json_parser_->Start();
 
   if (icon_url_.is_empty()) {
     icon_decode_complete_ = true;
   } else {
     // No existing |icon_fetcher_| to avoid unbalanced AddRef().
     CHECK(!icon_fetcher_.get());
     AddRef();  // Balanced in OnFetchComplete().
     icon_fetcher_.reset(new chrome::BitmapFetcher(icon_url_, this));
     icon_fetcher_->Init(
@@ skipping 28 matching lines @@
     scoped_ptr<base::Value> result) {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   manifest_parse_complete_ = true;
   const base::DictionaryValue* value;
   if (result->GetAsDictionary(&value))
     parsed_manifest_.reset(value->DeepCopy());
   else
     parse_error_ = Delegate::MANIFEST_ERROR;
 
   ReportResultsIfComplete();
-  Release();  // Balanced in Start().
 }
 
 void WebstoreInstallHelper::OnJSONParseFailed(
     const std::string& error_message) {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   manifest_parse_complete_ = true;
   error_ = error_message;
   parse_error_ = Delegate::MANIFEST_ERROR;
   ReportResultsIfComplete();
-  Release();  // Balanced in Start().
 }
 
 void WebstoreInstallHelper::ReportResultsIfComplete() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!icon_decode_complete_ || !manifest_parse_complete_)
     return;
 
   if (error_.empty() && parsed_manifest_)
     delegate_->OnWebstoreParseSuccess(id_, icon_, parsed_manifest_.release());
   else
     delegate_->OnWebstoreParseFailure(id_, parse_error_, error_);
 }
 
 }  // namespace extensions