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

chrome/browser/sync/glue/sync_backend_host.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 #pragma once
 
 #include <string>
 
@@ skipping 20 matching lines @@
 #include "sync/util/report_unrecoverable_error_function.h"
 #include "sync/util/unrecoverable_error_handler.h"
 #include "sync/util/weak_handle.h"
 
 class MessageLoop;
 class Profile;
 
 namespace browser_sync {
 
 class ChangeProcessor;
+struct Experiments;
 class JsBackend;
 class JsEventHandler;
 class SyncBackendRegistrar;
 class SyncPrefs;
 
 // SyncFrontend is the interface used by SyncBackendHost to communicate with
 // the entity that created it and, presumably, is interested in sync-related
 // activity.
 // NOTE: All methods will be invoked by a SyncBackendHost on the same thread
 // used to create that SyncBackendHost.
@@ skipping 63 matching lines @@
 
   // Called after we finish encrypting the current set of encrypted
   // types.
   virtual void OnEncryptionComplete() = 0;
 
   // Called to perform migration of |types|.
   virtual void OnMigrationNeededForTypes(
       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::Experiments& experiments) = 0;
 
   // Called when the sync cycle returns there is an user actionable error.
   virtual void OnActionableError(
       const browser_sync::SyncProtocolError& error) = 0;
 
  protected:
   // Don't delete through SyncFrontend interface.
   virtual ~SyncFrontend() {
   }
  private:
@@ skipping 378 matching lines @@
 
   // UI-thread cache of the last SyncSessionSnapshot received from syncapi.
   sessions::SyncSessionSnapshot last_snapshot_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_