[ios] Sets and registers prefs::kLastClearBrowsingDataTime on iOS

This will be used in future CL's to prevent certain behaviours
for some time after CBD has been triggered.

Bug: 1085419
Change-Id: I24d9a4878d05339911ec7bd95df6773ebc28f2dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359549
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Martin Šrámek <msramek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798942}

components/browsing_data/core/pref_names.cc

@@ -76,6 +76,7 @@ void RegisterBrowserUserPrefs(user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterBooleanPref(
       kDeleteSiteSettings, false,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+#else
   registry->RegisterInt64Pref(prefs::kLastClearBrowsingDataTime, 0);
 #endif  // !defined(OS_IOS)
 

ios/chrome/browser/ui/settings/clear_browsing_data/clear_browsing_data_table_view_controller.mm

@@ -7,6 +7,7 @@
 #include "base/mac/foundation_util.h"
 #include "base/metrics/user_metrics.h"
 #include "base/metrics/user_metrics_action.h"
+#include "components/browsing_data/core/pref_names.h"
 #include "components/prefs/pref_service.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/browsing_data/browsing_data_features.h"
@@ -341,6 +342,11 @@
     });
   };
 
+  // Set the kLastClearBrowsingDataTime Pref.
+  self.browserState->GetPrefs()->SetInt64(
+      browsing_data::prefs::kLastClearBrowsingDataTime,
+      base::Time::Now().ToTimeT());
+
   [self.dispatcher
       removeBrowsingDataForBrowserState:browserState
                              timePeriod:timePeriod