[Background Fetch] Sync provided OfflineContentProvider namespaces

This was causing callbacks (like GetVisualsForItem) to be lost since the
ContentID namespace did not match the registered OfflineContentProvider
namespace.

Change-Id: I009cbd2c38ac8d91c8c1efcd302be725c6588463
Reviewed-on: https://chromium-review.googlesource.com/1186734Reviewed-by: Peter Beverloo <peter@chromium.org>
Commit-Queue: Rayan Kanso <rayankans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585515}

chrome/browser/background_fetch/background_fetch_delegate_impl.cc

@@ -36,11 +36,13 @@ BackgroundFetchDelegateImpl::BackgroundFetchDelegateImpl(
     Profile* profile,
     const std::string& provider_namespace)
     : profile_(profile),
+      provider_namespace_(provider_namespace),
       offline_content_aggregator_(
           OfflineContentAggregatorFactory::GetForBrowserContext(profile)),
       weak_ptr_factory_(this) {
   DCHECK(profile_);
-  offline_content_aggregator_->RegisterProvider(provider_namespace, this);
+  DCHECK(!provider_namespace_.empty());
+  offline_content_aggregator_->RegisterProvider(provider_namespace_, this);
 }
 
 BackgroundFetchDelegateImpl::~BackgroundFetchDelegateImpl() = default;
@@ -65,10 +67,11 @@ void BackgroundFetchDelegateImpl::Shutdown() {
 BackgroundFetchDelegateImpl::JobDetails::JobDetails(JobDetails&&) = default;
 
 BackgroundFetchDelegateImpl::JobDetails::JobDetails(
-    std::unique_ptr<content::BackgroundFetchDescription> fetch_description)
+    std::unique_ptr<content::BackgroundFetchDescription> fetch_description,
+    const std::string& provider_namespace)
     : cancelled(false),
       offline_item(offline_items_collection::ContentId(
-          "background_fetch",
+          provider_namespace,
           fetch_description->job_unique_id)),
       fetch_description(std::move(fetch_description)) {
   UpdateOfflineItem();
@@ -207,7 +210,8 @@ void BackgroundFetchDelegateImpl::CreateDownloadJob(
   std::string job_unique_id = fetch_description->job_unique_id;
   DCHECK(!job_details_map_.count(job_unique_id));
   auto emplace_result = job_details_map_.emplace(
-      job_unique_id, JobDetails(std::move(fetch_description)));
+      job_unique_id,
+      JobDetails(std::move(fetch_description), provider_namespace_));
 
   const JobDetails& details = emplace_result.first->second;
   for (const auto& download_guid : details.fetch_description->current_guids) {

chrome/browser/background_fetch/background_fetch_delegate_impl.h

@@ -114,8 +114,9 @@ class BackgroundFetchDelegateImpl
  private:
   struct JobDetails {
     JobDetails(JobDetails&&);
-    explicit JobDetails(
-        std::unique_ptr<content::BackgroundFetchDescription> fetch_description);
+    JobDetails(
+        std::unique_ptr<content::BackgroundFetchDescription> fetch_description,
+        const std::string& provider_namespace);
     ~JobDetails();
 
     void UpdateOfflineItem();
@@ -150,6 +151,10 @@ class BackgroundFetchDelegateImpl
   // The profile this service is being created for.
   Profile* profile_;
 
+  // The namespace provided to the |offline_content_aggregator_| and used when
+  // creating Content IDs.
+  std::string provider_namespace_;
+
   // The BackgroundFetchDelegateImplFactory depends on the
   // DownloadServiceFactory, so |download_service_| should outlive |this|.
   download::DownloadService* download_service_ = nullptr;