Sync MDP: implement MemoryDumpProvider

components/sync/base/unique_position.cc

Index: components/sync/base/unique_position.cc
diff --git a/components/sync/base/unique_position.cc b/components/sync/base/unique_position.cc
index 1c8cdf87d8b2da7bafb9e53eac97d4a2685270b0..3a5615bb2d76eaaaaa1690ed8bcf8c5a07e3cdd6 100644
--- a/components/sync/base/unique_position.cc
+++ b/components/sync/base/unique_position.cc
@@ -14,6 +14,7 @@
 #include "base/rand_util.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/trace_event/memory_usage_estimators.h"
 #include "components/sync/protocol/unique_position.pb.h"
 #include "third_party/zlib/zlib.h"
 
@@ -617,4 +618,9 @@ bool UniquePosition::IsValidCompressed(const std::string& str) {
   return true;
 }
 
+size_t UniquePosition::EstimateMemoryUsage() const {
+  using base::trace_event::EstimateMemoryUsage;
+  return EstimateMemoryUsage(compressed_);
+}
+
 }  // namespace syncer