Register delete time period pref for Clear Browsing Data on iOS

This will be set via a time selector in the Clear Browsing Data UI on iOS.

BUG=620318

Review-Url: https://codereview.chromium.org/2184163002
Cr-Commit-Position: refs/heads/master@{#408373}

ios/chrome/browser/BUILD.gn

@@ -602,6 +602,7 @@ source_set("browser") {
     "//components/bookmarks/browser",
     "//components/browser_sync/browser",
     "//components/browser_sync/common",
+    "//components/browsing_data/core",
     "//components/browsing_data_ui",
     "//components/component_updater",
     "//components/content_settings/core/browser",

ios/chrome/browser/DEPS

@@ -8,6 +8,7 @@ include_rules = [
   "+components/bookmarks",
   "+components/browser_sync/browser",
   "+components/browser_sync/common",
+  "+components/browsing_data/core",
   "+components/browsing_data_ui",
   "+components/component_updater",
   "+components/content_settings/core",

ios/chrome/browser/prefs/browser_prefs.mm

@@ -5,6 +5,7 @@
 #include "ios/chrome/browser/prefs/browser_prefs.h"
 
 #include "components/autofill/core/browser/autofill_manager.h"
+#include "components/browsing_data/core/pref_names.h"
 #include "components/content_settings/core/browser/host_content_settings_map.h"
 #include "components/dom_distiller/core/distilled_page_prefs.h"
 #include "components/flags_ui/pref_service_flags_storage.h"
@@ -138,6 +139,9 @@ void RegisterBrowserStatePrefs(user_prefs::PrefRegistrySyncable* registry) {
   // Register prefs used by Clear Browsing Data UI.
   registry->RegisterIntegerPref(
       prefs::kClearBrowsingDataHistoryNoticeShownTimes, 0);
+  registry->RegisterIntegerPref(
+      browsing_data::prefs::kDeleteTimePeriod, 0,
+      user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
 
   ios::GetChromeBrowserProvider()->RegisterProfilePrefs(registry);
 }

ios/chrome/ios_chrome.gyp

@@ -52,6 +52,7 @@
         '../../components/components.gyp:bookmarks_browser',
         '../../components/components.gyp:browser_sync_browser',
         '../../components/components.gyp:browser_sync_common',
+        '../../components/components.gyp:browsing_data_core',
         '../../components/components.gyp:component_updater',
         '../../components/components.gyp:content_settings_core_browser',
         '../../components/components.gyp:cookie_config',