[Sync] Rename syncable_prefs to sync_preferences.

ios/chrome/browser/browser_state/chrome_browser_state.h

Index: ios/chrome/browser/browser_state/chrome_browser_state.h
diff --git a/ios/chrome/browser/browser_state/chrome_browser_state.h b/ios/chrome/browser/browser_state/chrome_browser_state.h
index 31548b912ce1939f09463a194119e870c5ad5f93..1295a4c197499e9dac4b98f09b6f155f02e37c42 100644
--- a/ios/chrome/browser/browser_state/chrome_browser_state.h
+++ b/ios/chrome/browser/browser_state/chrome_browser_state.h
@@ -33,7 +33,7 @@ class SSLConfigService;
 class URLRequestInterceptor;
 }
 
-namespace syncable_prefs {
+namespace sync_preferences {
 class PrefServiceSyncable;
 }
 
@@ -96,8 +96,8 @@ class ChromeBrowserState : public web::BrowserState {
   virtual ChromeBrowserStateIOData* GetIOData() = 0;
 
   // Retrieves a pointer to the PrefService that manages the preferences as
-  // a syncable_prefs::PrefServiceSyncable.
-  virtual syncable_prefs::PrefServiceSyncable* GetSyncablePrefs();
+  // a sync_preferences::PrefServiceSyncable.
+  virtual sync_preferences::PrefServiceSyncable* GetSyncablePrefs();
 
   // Deletes all network related data since |time|. It deletes transport
   // security state since |time| and it also deletes HttpServerProperties data.