Resource Load Statistics: Make network process calls only for the process pool that...

Resource Load Statistics: Make network process calls only for the process pool that the page belongs to
https://bugs.webkit.org/show_bug.cgi?id=187206
<rdar://problem/41659160>

Reviewed by Chris Dumez.

Instead of iterating over all process pools, we should resolve which
process pool the page belongs to and call the network process only for
that pool. This is especially important since we use WTFMove for the
completion handlers.

This patch also renames "callback" to "completionHandler" for
the functions touched.

A FIXME comment is added to WebsiteDataStore::getAllStorageAccessEntries()
where we currently don't have a page ID to do the lookup with.

* UIProcess/WebsiteData/WebsiteDataStore.cpp:
(WebKit::WebsiteDataStore::updatePrevalentDomainsToPartitionOrBlockCookies):
(WebKit::WebsiteDataStore::hasStorageAccessForFrameHandler):
(WebKit::WebsiteDataStore::getAllStorageAccessEntries):
(WebKit::WebsiteDataStore::grantStorageAccessHandler):
(WebKit::WebsiteDataStore::hasStorageAccess):
(WebKit::WebsiteDataStore::requestStorageAccess):
(WebKit::WebsiteDataStore::grantStorageAccess):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@233384 268f45cc-cd09-0410-ab3c-d52691b4dbfc