[Sync] Add support for automatic enabling of syncing tab favicons.

chrome/browser/sync/glue/sync_backend_host.h

Index: chrome/browser/sync/glue/sync_backend_host.h
diff --git a/chrome/browser/sync/glue/sync_backend_host.h b/chrome/browser/sync/glue/sync_backend_host.h
index 691586a0e956c8d34e30ae6618a243f87e1178ac..7a5b463e1e382ccc351b1950b2ae221b05adc80b 100644
--- a/chrome/browser/sync/glue/sync_backend_host.h
+++ b/chrome/browser/sync/glue/sync_backend_host.h
@@ -41,6 +41,7 @@ class ChangeProcessor;
 class JsBackend;
 class JsEventHandler;
 class SyncBackendRegistrar;
+struct SyncExperiments;
 class SyncPrefs;
 
 // SyncFrontend is the interface used by SyncBackendHost to communicate with
@@ -121,7 +122,8 @@ class SyncFrontend {
       syncable::ModelTypeSet types) = 0;
 
   // Inform the Frontend that new datatypes are available for registration.
-  virtual void OnDataTypesChanged(syncable::ModelTypeSet to_add) = 0;
+  virtual void OnExperimentsChanged(
+      const browser_sync::SyncExperiments& experiments) = 0;
 
   // Called when the sync cycle returns there is an user actionable error.
   virtual void OnActionableError(