Disable sync for Lightspeed experimentation.

chrome/browser/sync/profile_sync_service.cc

Index: chrome/browser/sync/profile_sync_service.cc
diff --git a/chrome/browser/sync/profile_sync_service.cc b/chrome/browser/sync/profile_sync_service.cc
index 61ad4f310473e5db1bdeb9539e9d4febdfee8d8b..e209c77f09a27cecbc6d93c43d1d7e4451e9c659 100644
--- a/chrome/browser/sync/profile_sync_service.cc
+++ b/chrome/browser/sync/profile_sync_service.cc
@@ -75,6 +75,7 @@
 #include "components/sync_driver/pref_names.h"
 #include "components/sync_driver/system_encryptor.h"
 #include "components/sync_driver/user_selectable_sync_type.h"
+#include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
@@ -2455,6 +2456,11 @@ void ProfileSyncService::SyncEvent(SyncEventCodes code) {
 
 // static
 bool ProfileSyncService::IsSyncEnabled() {
+  // Disable sync experimentally to measure impact on startup time.
+  // TODO(mlerman): Remove this after the experiment. crbug.com/454788

[Alexei Svitkine (slow), 2015/02/19 22:04:08]

Nit: Add this comment above the other variations check too.

[Mike Lerman, 2015/02/20 16:38:02]

Done.

+  if (!variations::GetVariationParamValue("LightSpeed", "DisableSync").empty())
+      return false;

[Bernhard Bauer, 2015/02/18 21:12:44]

Nit: indent two spaces less.

[Mike Lerman, 2015/02/20 16:38:01]

Done.

+
   // We have switches::kEnableSync just in case we need to change back to
   // sync-disabled-by-default on a platform.
   return !base::CommandLine::ForCurrentProcess()->HasSwitch(