[Background Fetch] Remove records_ from BackgroundFetchRegistration.

This had been introduced to simplify access to active fetches, but has
the following issues:
1. It makes match() and matchAll() inconsistent with Cache API's match()
and matchAll(), which return new independently-consumable response(s) every
time they're called.
2. It breaks retries for responses, when downloading from a server that
doesn't support resuming of downloads.

For details, see
https://docs.google.com/document/d/1CrbWrnnshhyp_SfiAeuODpnQX36GK3Bsi19rXQGez6Q/edit?usp=sharing

The CL also updates the WPT test accordingly.

Bug: 875201
Change-Id: I2c33717cbee36f0d707e814506c0bae9b5a4f31f
Reviewed-on: https://chromium-review.googlesource.com/c/1355121
Commit-Queue: Mugdha Lakhani <nator@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613079}

third_party/blink/renderer/modules/background_fetch/background_fetch_registration.cc

@@ -88,8 +88,6 @@ void BackgroundFetchRegistration::OnProgress(
   result_ = result;
   failure_reason_ = failure_reason;
 
-  // TODO(crbug.com/875201): Update records in |records_|.
-
   ExecutionContext* context = GetExecutionContext();
   if (!context || context->IsContextDestroyed())
     return;
@@ -242,21 +240,11 @@ void BackgroundFetchRegistration::DidGetMatchingRequests(
   ScriptState::Scope scope(script_state);
   HeapVector<Member<BackgroundFetchRecord>> to_return;
   to_return.ReserveInitialCapacity(settled_fetches.size());
+
   for (auto& fetch : settled_fetches) {
-    // If there isn't a record for this fetch in records_ already, create one.
-    auto iter = records_.find(fetch->request->url);
-    BackgroundFetchRecord* record = nullptr;
-    if (iter == records_.end()) {
     Request* request = Request::Create(script_state, *(fetch->request));
-      auto* new_record =
+    auto* record =
         MakeGarbageCollected<BackgroundFetchRecord>(request, script_state);
-      DCHECK(new_record);
-      records_.Set(request->url(), new_record);
-
-      record = new_record;
-    } else {
-      record = iter->value;
-    }
 
     UpdateRecord(record, fetch->response);
     to_return.push_back(record);
@@ -268,11 +256,13 @@ void BackgroundFetchRegistration::DidGetMatchingRequests(
       resolver->Resolve();
       return;
     }
+
     DCHECK_EQ(settled_fetches.size(), 1u);
     DCHECK_EQ(to_return.size(), 1u);
     resolver->Resolve(to_return[0]);
     return;
   }
+
   resolver->Resolve(to_return);
 }
 
@@ -373,7 +363,6 @@ void BackgroundFetchRegistration::Dispose() {
 
 void BackgroundFetchRegistration::Trace(Visitor* visitor) {
   visitor->Trace(registration_);
-  visitor->Trace(records_);
   EventTargetWithInlineData::Trace(visitor);
 }
 

third_party/blink/renderer/modules/background_fetch/background_fetch_registration.h

@@ -12,7 +12,6 @@
 #include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
 #include "third_party/blink/renderer/platform/heap/garbage_collected.h"
 #include "third_party/blink/renderer/platform/heap/handle.h"
-#include "third_party/blink/renderer/platform/weborigin/kurl_hash.h"
 #include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
 
 namespace blink {
@@ -122,9 +121,6 @@ class BackgroundFetchRegistration final
 
   Member<ServiceWorkerRegistration> registration_;
 
-  // TODO(crbug.com/774054): Update the key once we support duplicate requests.
-  HeapHashMap<KURL, Member<BackgroundFetchRecord>> records_;
-
   // Corresponds to IDL 'id' attribute. Not unique - an active registration can
   // have the same |developer_id_| as one or more inactive registrations.
   String developer_id_;

third_party/blink/web_tests/external/wpt/background-fetch/fetch.https.window.js

@@ -321,6 +321,6 @@ backgroundFetchTest(async (test, backgroundFetch) => {
 
   assert_true(results[1].url.includes('resources/feature-name.txt'));
   assert_equals(results[1].status, 200);
-  assert_equals(results[1].text, 'error');
+  assert_equals(results[1].text, 'Background Fetch');
 
 }, 'Matching multiple times on the same request works as expected.');