Garbage collect sync local cache GUIDs based on time

There's no point in remembering very old cache GUIDs since features
anyway filter for recent devices, so let's implement a
garbage-collection logic for the cache GUIDs stored in prefs.

Bug: 989340
Change-Id: I1b1f84e3026471f8f687caa54922e2ea43bafaba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1827435
Reviewed-by: David Roger <[email protected]>
Reviewed-by: Marc Treib <[email protected]>
Commit-Queue: Mikel Astiz <[email protected]>
Auto-Submit: Mikel Astiz <[email protected]>
Cr-Commit-Position: refs/heads/master@{#702052}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 086c510..fd5b9c66 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -1193,4 +1193,7 @@
   profile_prefs->ClearPref(kGoogleServicesUserAccountId);
   profile_prefs->ClearPref(
       kDataReductionProxySavingsClearedNegativeSystemClock);
+
+  // Added 10/2019.
+  syncer::DeviceInfoPrefs::MigrateRecentLocalCacheGuidsPref(profile_prefs);
 }