Sync MDP: implement MemoryDumpProvider

components/sync/syncable/syncable_id.h

Index: components/sync/syncable/syncable_id.h
diff --git a/components/sync/syncable/syncable_id.h b/components/sync/syncable/syncable_id.h
index f96fb83f185a7ed13df6dfa0691caabc518e372d..1bb74cf6a14778b533b8b6890f3f9d95ba423e7c 100644
--- a/components/sync/syncable/syncable_id.h
+++ b/components/sync/syncable/syncable_id.h
@@ -12,6 +12,7 @@
 #include <string>
 
 #include "base/containers/hash_tables.h"
+#include "base/trace_event/memory_usage_estimators.h"
 
 namespace base {
 class StringValue;
@@ -96,6 +97,10 @@ class Id {
   std::string s_;
 };
 
+inline size_t EstimateMemoryUsage(const Id& id) {
+  return base::trace_event::EstimateMemoryUsage(id.value());
+}
+
 }  // namespace syncable
 }  // namespace syncer