[WIP][tracing] Add memory dump provider for sync Directory

sync/syncable/directory.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SYNC_SYNCABLE_DIRECTORY_H_
 #define SYNC_SYNCABLE_DIRECTORY_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 12 matching lines @@
 #include "sync/api/attachments/attachment_id.h"
 #include "sync/base/sync_export.h"
 #include "sync/internal_api/public/util/weak_handle.h"
 #include "sync/syncable/dir_open_result.h"
 #include "sync/syncable/entry.h"
 #include "sync/syncable/entry_kernel.h"
 #include "sync/syncable/metahandle_set.h"
 #include "sync/syncable/parent_child_index.h"
 #include "sync/syncable/syncable_delete_journal.h"
 
+namespace base {
+namespace trace_event {
+class ProcessMemoryDump;
+}
+}
+
 namespace syncer {
 
 class Cryptographer;
 class TestUserShare;
 class UnrecoverableErrorHandler;
 
 namespace syncable {
 
 class BaseTransaction;
 class BaseWriteTransaction;
@@ skipping 233 matching lines @@
       ModelType type,
       std::string* value_out) const;
   void SetDownloadProgress(
       ModelType type,
       const sync_pb::DataTypeProgressMarker& value);
   bool HasEmptyDownloadProgress(ModelType type) const;
 
   // Gets the total number of entries in the directory.
   size_t GetEntriesCount() const;
 
+  size_t GetApproximateMemoryUsage();
+
+  // Adds memory statistics to |pmd| for chrome://tracing.
+  void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd);
+
   // Gets/Increments transaction version of a model type. Must be called when
   // holding kernel mutex.
   int64_t GetTransactionVersion(ModelType type) const;
   void IncrementTransactionVersion(ModelType type);
 
   // Getter/setters for the per datatype context.
   void GetDataTypeContext(BaseTransaction* trans,
                           ModelType type,
                           sync_pb::DataTypeContext* context) const;
   void SetDataTypeContext(BaseWriteTransaction* trans,
@@ skipping 357 matching lines @@
 
   base::WeakPtrFactory<Directory> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Directory);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_DIRECTORY_H_