Fix race conditions in ImageDecoder.

chrome/browser/apps/drive/drive_app_converter.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 "chrome/browser/apps/drive/drive_app_converter.h"
 
 #include <algorithm>
 #include <set>
 
 #include "base/logging.h"
@@ skipping 19 matching lines @@
 // url is passed from a DriveAppInfo and should follow icon url definition
 // in Drive API:
 //   https://developers.google.com/drive/v2/reference/apps#resource
 // Each icon url represents a single image associated with a certain size.
 class DriveAppConverter::IconFetcher : public net::URLFetcherDelegate,
                                        public ImageDecoder::ImageRequest {
  public:
   IconFetcher(DriveAppConverter* converter,
               const GURL& icon_url,
               int expected_size)
-      : ImageRequest(
-            BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI)),
-        converter_(converter),
+      : converter_(converter),
         icon_url_(icon_url),
         expected_size_(expected_size) {}
   ~IconFetcher() override {}
 
   void Start() {
     fetcher_.reset(
         net::URLFetcher::Create(icon_url_, net::URLFetcher::GET, this));
     fetcher_->SetRequestContext(converter_->profile_->GetRequestContext());
     fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SAVE_COOKIES);
     fetcher_->Start();
@@ skipping 143 matching lines @@
     return;
   }
 
   extension_ = crx_installer_->extension();
   is_new_install_ = success && crx_installer_->current_version().empty();
   PostInstallCleanUp();
 
   finished_callback_.Run(this, success);
   // |finished_callback_| could delete this.
 }