Use IOSImageDataFetcherWrapper in BrowserViewController

components/image_fetcher/image_data_fetcher.h

 // 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.
 
 #ifndef COMPONENTS_IMAGE_FETCHER_IMAGE_DATA_FETCHER_H_
 #define COMPONENTS_IMAGE_FETCHER_IMAGE_DATA_FETCHER_H_
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "components/data_use_measurement/core/data_use_user_data.h"
 #include "net/url_request/url_fetcher_delegate.h"
+#include "net/url_request/url_request.h"
 #include "url/gurl.h"
 
 namespace net {
 class URLFetcher;
 class URLRequestContextGetter;
 }  // namespace net
 
 namespace image_fetcher {
 
 class ImageDataFetcher : public net::URLFetcherDelegate {
  public:
   using ImageDataFetcherCallback =
       base::Callback<void(const std::string& image_data)>;
 
   using DataUseServiceName = data_use_measurement::DataUseUserData::ServiceName;
 
   explicit ImageDataFetcher(
       net::URLRequestContextGetter* url_request_context_getter);
   ~ImageDataFetcher() override;
 
   // Sets a service name against which to track data usage.
   void SetDataUseServiceName(DataUseServiceName data_use_service_name);
 
+  // Helper to fetches images data without a referrer.

[Marc Treib, 2017/02/02 15:19:13]

s/fetches images/fetch image/

Though I might do the comments the other way around: Have the "main" comment
here, and then on the overload below, say just "Like above, but lets the caller
set a referrer". (Not a big deal either way)

[gambard, 2017/02/03 12:11:34]

Done.

+  void FetchImageData(const GURL& image_url,
+                      const ImageDataFetcherCallback& callback);
+
   // Fetches the raw image bytes from the given |image_url| and calls the given
   // |callback|. The callback is run even if fetching the URL fails. In case
   // of an error an empty string is passed to the callback.
+  // The |referrer| and |referrer_policy| will be passed on to the underlying
+  // URLFetcher.
   void FetchImageData(const GURL& image_url,
-                      const ImageDataFetcherCallback& callback);
+                      const ImageDataFetcherCallback& callback,
+                      const std::string& referrer,
+                      net::URLRequest::ReferrerPolicy referrer_policy);
 
  private:
   struct ImageDataFetcherRequest;
 
   // Method inherited from URLFetcherDelegate
   void OnURLFetchComplete(const net::URLFetcher* source) override;
 
   // All active image url requests.
   std::map<const net::URLFetcher*, std::unique_ptr<ImageDataFetcherRequest>>
       pending_requests_;
 
   scoped_refptr<net::URLRequestContextGetter> url_request_context_getter_;
 
   DataUseServiceName data_use_service_name_;
 
   // The next ID to use for a newly created URLFetcher. Each URLFetcher gets an
   // id when it is created. The |url_fetcher_id_| is incremented by one for each
   // newly created URLFetcher. The URLFetcher ID can be used during testing to
   // get individual URLFetchers and modify their state. Outside of tests this ID
   // is not used.
   int next_url_fetcher_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDataFetcher);
 };
 
 }  // namespace image_fetcher
 
 #endif  // COMPONENTS_IMAGE_FETCHER_IMAGE_DATA_FETCHER_H_