[BackgroundFetch] Part 1: Remove BackgroundFetchSettledFetches.

This removes BackgroundFetchSettledFetches from blink, idl files,
and the WPT tests.

In a follow up CL I'll remove it from all the event dispatcher code
on the browser side.

This fix also makes cache_query_params optional in MatchRequests() in mojo.
This is required because otherwise the mojo bindings logic crashes the renderer
when we try to pass in a nullptr for cache_query_params from blink.

Bug: 869918, 863016
Change-Id: Ifa933451f98f82902d8455ba5401c629c8c24811
Reviewed-on: https://chromium-review.googlesource.com/1186735
Commit-Queue: Mugdha Lakhani <[email protected]>
Reviewed-by: Peter Beverloo <[email protected]>
Reviewed-by: Rayan Kanso <[email protected]>
Reviewed-by: Dmitry Gozman <[email protected]>
Reviewed-by: Tom Sepez <[email protected]>
Reviewed-by: Kentaro Hara <[email protected]>
Cr-Commit-Position: refs/heads/master@{#585847}

Author: Mugdha Lakhani

background-fetch/service_workers/sw.js

@@ -1,20 +1,21 @@
 
 importScripts('sw-helpers.js');
 
-async function getFetchResult(settledFetch) {
-  if (!settledFetch.response)
+async function getFetchResult(record) {
+  response = await record.responseReady;
+  if (!response)
     return Promise.resolve(null);
 
   return {
-    url: settledFetch.response.url,
-    status: settledFetch.response.status,
-    text: await settledFetch.response.text(),
+    url: response.url,
+    status: response.status,
+    text: await response.text(),
   };
 }
 
 self.addEventListener('backgroundfetchsuccess', event => {
   event.waitUntil(
-    event.fetches.values()
-      .then(fetches => Promise.all(fetches.map(fetch => getFetchResult(fetch))))
+    event.registration.matchAll()
+      .then(records => Promise.all(records.map(record => getFetchResult(record))))
       .then(results => sendMessageToDocument({ type: event.type, results })));
 });