Revert of Bring up of the enhanced bookmarks cluster service.

components/enhanced_bookmarks/enhanced_bookmark_model.cc

Index: components/enhanced_bookmarks/enhanced_bookmark_model.cc
diff --git a/components/enhanced_bookmarks/enhanced_bookmark_model.cc b/components/enhanced_bookmarks/enhanced_bookmark_model.cc
index 7f89f8297eb6ca451377207e7e39fe0958063fb3..6ffcaf392035cd2101e9fbbf356985a9464c6630 100644
--- a/components/enhanced_bookmarks/enhanced_bookmark_model.cc
+++ b/components/enhanced_bookmarks/enhanced_bookmark_model.cc
@@ -91,18 +91,15 @@
 }
 
 EnhancedBookmarkModel::~EnhancedBookmarkModel() {
-  Shutdown();
 }
 
 void EnhancedBookmarkModel::Shutdown() {
-  if (bookmark_model_) {
-    FOR_EACH_OBSERVER(EnhancedBookmarkModelObserver,
-                      observers_,
-                      EnhancedBookmarkModelShuttingDown());
-    weak_ptr_factory_.InvalidateWeakPtrs();
-    bookmark_model_->RemoveObserver(this);
-    bookmark_model_ = NULL;
-  }
+  FOR_EACH_OBSERVER(EnhancedBookmarkModelObserver,
+                    observers_,
+                    EnhancedBookmarkModelShuttingDown());
+  weak_ptr_factory_.InvalidateWeakPtrs();
+  bookmark_model_->RemoveObserver(this);
+  bookmark_model_ = NULL;
 }
 
 void EnhancedBookmarkModel::AddObserver(