Simplify the ImageDataFetcher code.

components/image_fetcher/image_data_fetcher.cc

 // Copyright 2016 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 "components/image_fetcher/image_data_fetcher.h"
 
 #include "net/base/load_flags.h"
 #include "net/url_request/url_fetcher.h"
-#include "net/url_request/url_fetcher_delegate.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "net/url_request/url_request_status.h"
 #include "url/gurl.h"
 
 namespace image_fetcher {
 
-// An active image URL fetcher request. The class contains any related request
-// state and logic for handling a single image url request.
-class ImageDataFetcher::ImageDataFetcherRequest
-    : public net::URLFetcherDelegate {
- public:
-  ImageDataFetcherRequest(const GURL& url,
-                          const ImageDataFetcherCallback& callback,
-                          ImageDataFetcher* image_url_fetcher);
-  ~ImageDataFetcherRequest() override {}
+// An active image URL fetcher request. The struct contains the related requests
+// state.
+struct ImageDataFetcher::ImageDataFetcherRequest {
+  ImageDataFetcherRequest(const ImageDataFetcherCallback& callback,
+                          std::unique_ptr<net::URLFetcher> url_fetcher)
+    : callback(callback),
+      url_fetcher(std::move(url_fetcher)) {}
 
-  // Sends the URL requests.
-  void Start(net::URLRequestContextGetter* request_context);
-
- private:
-  // Method inherited from URLFetcherDelegate
-  void OnURLFetchComplete(const net::URLFetcher* source) override;
-
-  // The URL of the image to fetch.
-  const GURL url_;
+  ~ImageDataFetcherRequest() {}
 
   // The callback to run after the image data was fetched. The callback will
   // be run even if the image data could not be fetched successfully.
-  ImageDataFetcherCallback callback_;
+  ImageDataFetcherCallback callback;
 
-  // The ImageDataFetcher that owns the ImageDataFetcherRequest.
-  ImageDataFetcher* image_url_fetcher_;
-
-  std::unique_ptr<net::URLFetcher> url_fetcher_;
-
-  DISALLOW_COPY_AND_ASSIGN(ImageDataFetcherRequest);
+  std::unique_ptr<net::URLFetcher> url_fetcher;
 };
 
-ImageDataFetcher::ImageDataFetcherRequest::ImageDataFetcherRequest(
-    const GURL& url,
-    const ImageDataFetcherCallback& callback,
-    ImageDataFetcher* image_url_fetcher)
-    : url_(url),
-      callback_(callback),
-      image_url_fetcher_(image_url_fetcher) {
-}
-
-void ImageDataFetcher::ImageDataFetcherRequest::Start(
-    net::URLRequestContextGetter* request_context) {
-  DCHECK(!url_fetcher_);
-
-  url_fetcher_ = net::URLFetcher::Create(url_, net::URLFetcher::GET, this);
-  url_fetcher_->SetRequestContext(request_context);
-  url_fetcher_->Start();
-}
-
-void ImageDataFetcher::ImageDataFetcherRequest::OnURLFetchComplete(
-    const net::URLFetcher* source) {
-  // An empty string is passed to the callback in case on an unsuccessfull URL
-  // request.
-  std::string image_data;
-  if (source->GetStatus().status() == net::URLRequestStatus::SUCCESS) {
-    source->GetResponseAsString(&image_data);
-  }
-  callback_.Run(image_data);
-
-  // Remove the completed ImageDataFetcherRequest from the internal request
-  // queue. This must be last in the method.
-  image_url_fetcher_->RemoveImageDataFetcherRequest(url_);
-}
-
 ImageDataFetcher::ImageDataFetcher(
     net::URLRequestContextGetter* url_request_context_getter)
     : url_request_context_getter_(url_request_context_getter) {}
 
 ImageDataFetcher::~ImageDataFetcher() {}
 
 void ImageDataFetcher::FetchImageData(
     const GURL& url, const ImageDataFetcherCallback& callback) {
+  std::unique_ptr<net::URLFetcher> url_fetcher =
+      net::URLFetcher::Create(url, net::URLFetcher::GET, this);
+
   std::unique_ptr<ImageDataFetcherRequest> request(
-      new ImageDataFetcherRequest(url, callback, this));
-  request->Start(url_request_context_getter_.get());
-  pending_requests_[url] = std::move(request);
+      new ImageDataFetcherRequest(callback, std::move(url_fetcher)));
+  request->url_fetcher->SetRequestContext(url_request_context_getter_.get());
+  request->url_fetcher->Start();
+
+  pending_requests_[request->url_fetcher.get()] = std::move(request);
 }
 
-void ImageDataFetcher::RemoveImageDataFetcherRequest(const GURL& image_url) {
-  size_t count = pending_requests_.erase(image_url);
-  DCHECK(count);
+void ImageDataFetcher::OnURLFetchComplete(const net::URLFetcher* source) {
+  auto request_iter = pending_requests_.find(source);
+  DCHECK(request_iter != pending_requests_.end());
+
+  std::string image_data;
+  if (source->GetStatus().status() == net::URLRequestStatus::SUCCESS) {
+    source->GetResponseAsString(&image_data);
+  }
+  request_iter->second->callback.Run(image_data);
+
+  // Remove the finished request.
+  pending_requests_.erase(request_iter);
 }
 
 }  // namespace image_fetcher