Create the IOSImageDataFetcher

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 "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)>;
+      base::Callback<void(const std::string& image_data,
+                          const net::URLFetcher* source)>;

[Marc Treib, 2017/01/25 10:37:55]

You'll have to update the tests for the new param. It'd also be great to add
some tests for the new behavior.

That said, this seems like a somewhat weird interface: This class is supposed to
abstract away the details of the URLFetcher etc.
What exact info does your client need? Would it be enough to return some sort of
error code instead of the URLFetcher?

[markusheintz_, 2017/01/25 12:03:45]

It would be great to learn what motivates this change.

[gambard, 2017/01/25 12:09:45]

The IOSImageDataFetcher class is using the URLFetcher to get the mime type (to
check if it is WebP), the http response (needed by some classes in the callback,
I need to add it) and the original url (to see if it is a data URI or not).
Considering that, I think I need it in the callback I am using to decode the
WebP. With the architecture as it is, it seemed to be the smallest change.

 
   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);
 
@@ skipping 23 matching lines @@
   // 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_