Use component ImageFetcher instead of iOS one.

ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.cc

 // Copyright 2015 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 "ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.h"
 
 #include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/json/json_reader.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/default_clock.h"
 #include "base/values.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/image_fetcher/image_decoder.h"
 #include "components/image_fetcher/image_fetcher.h"
+#include "components/image_fetcher/image_fetcher_impl.h"
 #include "components/keyed_service/core/service_access_type.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/ntp_snippets/bookmarks/bookmark_suggestions_provider.h"
 #include "components/ntp_snippets/category_rankers/category_ranker.h"
 #include "components/ntp_snippets/category_rankers/click_based_category_ranker.h"
 #include "components/ntp_snippets/category_rankers/constant_category_ranker.h"
 #include "components/ntp_snippets/content_suggestions_service.h"
 #include "components/ntp_snippets/features.h"
 #include "components/ntp_snippets/ntp_snippets_constants.h"
 #include "components/ntp_snippets/remote/persistent_scheduler.h"
 #include "components/ntp_snippets/remote/remote_suggestions_database.h"
 #include "components/ntp_snippets/remote/remote_suggestions_fetcher.h"
 #include "components/ntp_snippets/remote/remote_suggestions_provider_impl.h"
 #include "components/ntp_snippets/remote/remote_suggestions_status_service.h"
 #include "components/ntp_snippets/remote/scheduling_remote_suggestions_provider.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "components/version_info/version_info.h"
 #include "google_apis/google_api_keys.h"
 #include "ios/chrome/browser/application_context.h"
 #include "ios/chrome/browser/bookmarks/bookmark_model_factory.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/history/history_service_factory.h"
 #include "ios/chrome/browser/signin/oauth2_token_service_factory.h"
 #include "ios/chrome/browser/signin/signin_manager_factory.h"
-#include "ios/chrome/browser/suggestions/image_fetcher_impl.h"
 #include "ios/chrome/browser/suggestions/ios_image_decoder_impl.h"
 #include "ios/chrome/common/channel_info.h"
 #include "ios/web/public/browser_state.h"
 #include "ios/web/public/web_thread.h"
 #include "net/url_request/url_request_context_getter.h"
 
 using bookmarks::BookmarkModel;
 using history::HistoryService;
+using image_fetcher::ImageFetcherImpl;
 using ios::BookmarkModelFactory;
 using ntp_snippets::BookmarkSuggestionsProvider;
 using ntp_snippets::ContentSuggestionsService;
 using ntp_snippets::PersistentScheduler;
 using ntp_snippets::RemoteSuggestionsDatabase;
 using ntp_snippets::RemoteSuggestionsFetcher;
 using ntp_snippets::RemoteSuggestionsProviderImpl;
 using ntp_snippets::RemoteSuggestionsStatusService;
 using ntp_snippets::SchedulingRemoteSuggestionsProvider;
 using suggestions::CreateIOSImageDecoder;
-using suggestions::ImageFetcherImpl;
 
 namespace {
 
 void ParseJson(const std::string& json,
                const ntp_snippets::SuccessCallback& success_callback,
                const ntp_snippets::ErrorCallback& error_callback) {
   base::JSONReader json_reader;
   std::unique_ptr<base::Value> value = json_reader.ReadToValue(json);
   if (value) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
@@ skipping 74 matching lines @@
         OAuth2TokenServiceFactory::GetForBrowserState(chrome_browser_state);
     scoped_refptr<net::URLRequestContextGetter> request_context =
         browser_state->GetRequestContext();
     base::FilePath database_dir(
         browser_state->GetStatePath().Append(ntp_snippets::kDatabaseFolder));
     scoped_refptr<base::SequencedTaskRunner> task_runner =
         web::WebThread::GetBlockingPool()
             ->GetSequencedTaskRunnerWithShutdownBehavior(
                 base::SequencedWorkerPool::GetSequenceToken(),
                 base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
+
     auto suggestions_fetcher = base::MakeUnique<RemoteSuggestionsFetcher>(
         signin_manager, token_service, request_context, prefs, nullptr,
         base::Bind(&ParseJson), GetChannel() == version_info::Channel::STABLE
                                     ? google_apis::GetAPIKey()
                                     : google_apis::GetNonStableAPIKey(),
         service->user_classifier());
+
     auto provider = base::MakeUnique<RemoteSuggestionsProviderImpl>(
         service.get(), prefs, GetApplicationContext()->GetApplicationLocale(),
         service->category_ranker(), std::move(suggestions_fetcher),
-        base::MakeUnique<ImageFetcherImpl>(request_context.get(),
-                                           web::WebThread::GetBlockingPool()),
+        base::MakeUnique<ImageFetcherImpl>(
+            CreateIOSImageDecoder(web::WebThread::GetBlockingPool()),

[gambard, 2017/02/17 08:16:09]

I have used the same pool as the one used by the the ImageFetcher I am replacing
but I don't understand why we are not using "task_runner" here, as we do for the
ImageDecoder at line 171.

[noyau (Ping after 24h), 2017/02/17 10:04:18]

Probably historical. The taskrunner is createed on line 152 with the same
blocking pool anyway.

But I'm confused why there is a need for two image decoders? Is it a transient
state while you remove old code?

[Marc Treib, 2017/02/17 10:10:31]

Yup, transient - in fact, we have the same problem (both Fetcher and Decoder) in
other places. Removing the special iOS implementation of ImageFetcherImpl will
allow us to make this all better :)

[gambard, 2017/02/17 10:11:16]

No, the RemoteSuggestionsProviderImpl (living in components/ntp_snippets) takes
an ImageFetcher and an ImageDecoder.
This is because the images fetched are cached in a database, not decoded
(probably to save space). When retrieving them, it needs to decode it.
It can be removed once we remove the iOS implementation.

[Marc Treib, 2017/02/17 10:13:19]

Concurrent comments ftw :D

Some more detail: Once the same ImageFetcherImpl is used everywhere, my plan is
to add a "GetImageDecoder()" on it (since the fetcher contains a decoder
anyway). Then we won't have to pass the decoder in separately.

+            request_context.get()),
         CreateIOSImageDecoder(task_runner),
         base::MakeUnique<RemoteSuggestionsDatabase>(database_dir, task_runner),
         base::MakeUnique<RemoteSuggestionsStatusService>(signin_manager,
                                                          prefs));
 
     // TODO(jkrcal): Implement a persistent scheduler for iOS. crbug.com/676249
     auto scheduling_provider =
         base::MakeUnique<SchedulingRemoteSuggestionsProvider>(
             service.get(), std::move(provider),
             /*persistent_scheduler=*/nullptr, service->user_classifier(), prefs,
             base::MakeUnique<base::DefaultClock>());
     service->set_remote_suggestions_provider(scheduling_provider.get());
     service->set_remote_suggestions_scheduler(scheduling_provider.get());
     service->RegisterProvider(std::move(scheduling_provider));
   }
 
   return std::move(service);
 }