components: Add out-of-line copy ctors for complex classes.

components/bookmarks/browser/bookmark_node_data.h

Index: components/bookmarks/browser/bookmark_node_data.h
diff --git a/components/bookmarks/browser/bookmark_node_data.h b/components/bookmarks/browser/bookmark_node_data.h
index 34e940544ae4e10097dc61bf499b76691c093855..cbad37cd9a973edc67bd1bb5db029597ead83cdd 100644
--- a/components/bookmarks/browser/bookmark_node_data.h
+++ b/components/bookmarks/browser/bookmark_node_data.h
@@ -59,6 +59,7 @@ struct BookmarkNodeData {
   struct Element {
     Element();
     explicit Element(const BookmarkNode* node);
+    Element(const Element& other);
     ~Element();
 
     // If true, this element represents a URL.
@@ -99,6 +100,7 @@ struct BookmarkNodeData {
   static const char kClipboardFormatString[];
 
   BookmarkNodeData();
+  BookmarkNodeData(const BookmarkNodeData& other);
 
   // Created a BookmarkNodeData populated from the arguments.
   explicit BookmarkNodeData(const BookmarkNode* node);