Reduce the memory usage of bookmarks storage

components/bookmarks/browser/bookmark_client.h

Index: components/bookmarks/browser/bookmark_client.h
diff --git a/components/bookmarks/browser/bookmark_client.h b/components/bookmarks/browser/bookmark_client.h
index 7648cb9233c67d2cb808a51975f8f2d220fb0010..a402c7a3f759c8b4b497849e9d7f0e359cc440d3 100644
--- a/components/bookmarks/browser/bookmark_client.h
+++ b/components/bookmarks/browser/bookmark_client.h
@@ -7,6 +7,7 @@
 
 #include <map>
 #include <utility>
+#include <vector>
 
 #include "base/callback_forward.h"
 #include "base/task/cancelable_task_tracker.h"
@@ -66,6 +67,9 @@ class BookmarkClient {
   // |url_typed_count_map| must not be null.
   virtual void GetTypedCountForUrls(UrlTypedCountMap* url_typed_count_map);
 
+  // Metadata keys to be excluded from bookmark nodes in the storage.

[sky, 2017/05/26 03:07:38]

How about: Returns the set of keys that are not restored when reading bookmarks
back in.

[ssid, 2017/05/30 21:39:14]

Done.

+  virtual std::vector<std::string> ExecludedMetaKeys();

[sky, 2017/05/26 03:07:38]

GetExcludedMetaDataKeys().

[ssid, 2017/05/30 21:39:14]

Codec uses MetaInfo everywhere. Changed it to MetaInfo in all chnages in this
cl.

+
   // Returns whether the embedder wants permanent node |node|
   // to always be visible or to only show them when not empty.
   virtual bool IsPermanentNodeVisible(const BookmarkPermanentNode* node) = 0;