diff --git a/chrome/browser/extensions/sync_bundle.h b/chrome/browser/extensions/sync_bundle.h
index e37465c4..8ee58cf 100644
--- a/chrome/browser/extensions/sync_bundle.h
+++ b/chrome/browser/extensions/sync_bundle.h
@@ -5,20 +5,96 @@
 #ifndef CHROME_BROWSER_EXTENSIONS_SYNC_BUNDLE_H_
 #define CHROME_BROWSER_EXTENSIONS_SYNC_BUNDLE_H_
 
+#include <set>
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "sync/api/sync_change.h"
+#include "sync/api/sync_change_processor.h"
+#include "sync/api/sync_data.h"
+
+class ExtensionSyncService;
+
 namespace extensions {
 
 class Extension;
+class ExtensionSyncData;
 
-// Common interface between AppSyncBundle and ExtensionSyncBundle.
 class SyncBundle {
  public:
-  virtual ~SyncBundle() {}
+  explicit SyncBundle(ExtensionSyncService* sync_service);
+  ~SyncBundle();
+
+  void MergeDataAndStartSyncing(
+      const syncer::SyncDataList& initial_sync_data,
+      scoped_ptr<syncer::SyncChangeProcessor> sync_processor);
+
+  // Resets this class back to its default values, which will disable all
+  // syncing until StartSyncing is called again.
+  void Reset();
 
   // Has this bundle started syncing yet?
-  virtual bool IsSyncing() const = 0;
+  // Returns true if MergeDataAndStartSyncing has been called, false otherwise.
+  bool IsSyncing() const;
 
-  // Syncs changes to |extension|.
-  virtual void SyncChangeIfNeeded(const Extension& extension) = 0;
+  // Checks if the extension with the given |id| is synced.
+  bool HasExtensionId(const std::string& id) const;
+
+  // Whether the given extension should be included in the SyncDataList to be
+  // sent to the server. Returns false if there is pending data that should be
+  // used instead.
+  bool ShouldIncludeInLocalSyncDataList(const Extension& extension) const;
+
+  // Handles the given list of local SyncDatas. This updates the set of synced
+  // extensions as appropriate, and then pushes the corresponding SyncChanges
+  // to the server.
+  void PushSyncDataList(const syncer::SyncDataList& sync_data_list);
+
+  // Handles the sync deletion of the given extension. This updates the set of
+  // synced extensions as appropriate, and then pushes a SyncChange to the
+  // server.
+  void PushSyncDeletion(const std::string& extension_id,
+                        const syncer::SyncData& sync_data);
+
+  // Pushes any sync changes to |extension| to the server.
+  void PushSyncChangeIfNeeded(const Extension& extension);
+
+  // Applies the given SyncChange coming from the server.
+  void ApplySyncChange(const syncer::SyncChange& sync_change);
+
+  // Checks if the extension with the given |id| is pending to be synced.
+  bool HasPendingExtensionId(const std::string& id) const;
+
+  // Adds a pending extension to be synced.
+  void AddPendingExtension(const std::string& id,
+                           const ExtensionSyncData& sync_data);
+
+  // Returns a vector of all the pending sync data.
+  std::vector<ExtensionSyncData> GetPendingData() const;
+
+ private:
+  // Creates a SyncChange to add or update an extension.
+  syncer::SyncChange CreateSyncChange(const std::string& extension_id,
+                                      const syncer::SyncData& sync_data) const;
+
+  // Pushes the given list of SyncChanges to the server.
+  void PushSyncChanges(const syncer::SyncChangeList& sync_change_list);
+
+  void AddSyncedExtension(const std::string& id);
+  void RemoveSyncedExtension(const std::string& id);
+
+  // Changes an extension from being pending to synced.
+  void MarkPendingExtensionSynced(const std::string& id);
+
+  ExtensionSyncService* sync_service_;  // Owns us.
+
+  scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
+
+  std::set<std::string> synced_extensions_;
+
+  std::map<std::string, ExtensionSyncData> pending_sync_data_;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncBundle);
 };
 
 }  // namespace extensions