Use mime type for image extension

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 {
 
+struct RequestMetadata {

[gambard, 2017/02/09 13:44:12]

I don't know if this should be inside the class?

[Marc Treib, 2017/02/09 13:49:48]

That's mostly a matter of taste IMO. I tend to slightly prefer the nested class
approach, but I don't feel very strongly.

[sdefresne, 2017/02/09 13:55:28]

drive-by: having the class separate make it easier to refactor code or break
dependencies as it allows you to 1. forward-declare it (it is not possible to
forward-declare nested classes outside of the outer class declaration), 2. move
it to a separate file (allowing you to just include the header for that class if
you do not care about the outer class).

[gambard, 2017/02/09 15:10:32]

Actually, I have moved it to its own class.

[gambard, 2017/02/09 15:10:32]

Ok, I think I will let it outside the class as it is also used by the
IOSImageDataWrapper.

+  std::string mime_type;
+
+  bool operator==(const RequestMetadata& rhs) const {

[Marc Treib, 2017/02/09 13:49:48]

Are the equality operators required?

[sdefresne, 2017/02/09 13:55:28]

Even if they are required, they generally do not need to be methods but can be
free functions instead:

struct RequestMetaData {
  ...
};

bool operator==(const RequestMetaData& lhs, const RequestMetadata& rhs) {
  return ...
}

[gambard, 2017/02/09 15:10:32]

They are mainly here for testing (verifying that the received metadata is the
expected one).

+    return mime_type == rhs.mime_type;
+  }
+
+  bool operator!=(const RequestMetadata& rhs) const { return !operator==(rhs); }
+};
+
 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 RequestMetadata& request_metadata)>;
 
   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 29 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_