Modernize {Dictionary,List}PrefUpdate in /chrome/browser/login_detection

This cl replaces instances of DictionaryPrefUpdateDeprecated, which
wraps the deprecated base::DictionaryValue, with DictionaryPrefUpdate,
which wraps base::Value. This cl also does the equivalent for
ListPrefUpdateDeprecated. A range of other base::Value modernization
changes are made to allow these replacements and as drive-by fixes.
This cl handles the directory /chrome/browser/login_detection

This CL was uploaded by git cl split.

R=sophiechang@chromium.org

Bug: 1285745
Change-Id: I65e6f4b1cbd0219274e66ed1f92dec393765150e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3386007
Auto-Submit: Alex Turner <alexmt@chromium.org>
Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Commit-Queue: Sophie Chang <sophiechang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#958690}

chrome/browser/login_detection/login_detection_prefs.cc

@@ -38,8 +38,8 @@ void RemoveLoginDetectionData(PrefService* prefs) {
 }
 
 void SaveSiteToOAuthSignedInList(PrefService* pref_service, const GURL& url) {
-  DictionaryPrefUpdateDeprecated update(pref_service, kOAuthSignedInSitesPref);
-  base::DictionaryValue* dict = update.Get();
+  DictionaryPrefUpdate update(pref_service, kOAuthSignedInSitesPref);
+  base::Value* dict = update.Get();
   dict->SetKey(GetSiteNameForURL(url), base::TimeToValue(base::Time::Now()));
 
   // Try making space by removing sites having invalid sign-in time. This should