Fix NTP Omnibox suggestions not working with WKHTTPSystemCookieStore

Create a work around to force getAllCookies: completion handler to be executed
as soon as possible.
Workaround description and reasoning on the document:
https://docs.google.com/document/d/1aPNO5p44T-LMQT1Mocdll-SG7xq_9DIjb4N0oOTHZUs

Bug: 894540, 885218
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: I94090ed1b6b6aa1dce3f764bfa46bc1d700ddf4d
Reviewed-on: https://chromium-review.googlesource.com/c/1281685
Commit-Queue: Mohammad Refaat <mrefaat@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600078}

ios/web/net/cookies/wk_http_system_cookie_store.mm

@@ -48,6 +48,22 @@ bool ShouldIncludeForRequestUrl(NSHTTPCookie* cookie, const GURL& url) {
   return canonical_cookie.IncludeForRequestURL(url, options);
 }
 
+// Prioritizes queued WKHTTPCookieStore completion handlers to run as soon as
+// possible. This function is needed because some of WKHTTPCookieStore methods
+// completion handlers are not called until there is a WKWebView on the view
+// hierarchy.
+void PrioritizeWKHTTPCookieStoreCallbacks() {
+  // TODO(crbug.com/885218): Currently this hack is needed to fix
+  // crbug.com/885218. Remove when the behavior of
+  // [WKHTTPCookieStore getAllCookies:] changes.
+  NSSet* data_types = [NSSet setWithObject:WKWebsiteDataTypeCookies];
+  [[WKWebsiteDataStore defaultDataStore]
+      removeDataOfTypes:data_types
+          modifiedSince:[NSDate distantFuture]
+      completionHandler:^{
+      }];
+}
+
 }  // namespace
 
 WKHTTPSystemCookieStore::WKHTTPSystemCookieStore(
@@ -89,6 +105,7 @@ void WKHTTPSystemCookieStore::GetCookiesForURLAsync(
                 RunSystemCookieCallbackForCookies(std::move(shared_callback),
                                                   weak_time_manager, result);
               }];
+          PrioritizeWKHTTPCookieStoreCallbacks();
         } else {
           net::ReportGetCookiesForURLResult(
               net::SystemCookieStoreType::kWKHTTPSystemCookieStore, false);
@@ -115,6 +132,7 @@ void WKHTTPSystemCookieStore::GetAllCookiesAsync(
                 RunSystemCookieCallbackForCookies(std::move(shared_callback),
                                                   weak_time_manager, cookies);
               }];
+          PrioritizeWKHTTPCookieStoreCallbacks();
         } else {
           RunSystemCookieCallbackForCookies(std::move(shared_callback),
                                             weak_time_manager, @[]);