[Sync] Implement MemoryDumpProvider.

components/sync/syncable/entry_kernel.h

 // Copyright 2012 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 COMPONENTS_SYNC_SYNCABLE_ENTRY_KERNEL_H_
 #define COMPONENTS_SYNC_SYNCABLE_ENTRY_KERNEL_H_
 
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 207 matching lines @@
 
   // Set the dirty bit, and optionally add this entry's metahandle to
   // a provided index on dirty bits in |dirty_index|. Parameter may be null,
   // and will result only in setting the dirty bit of this entry.
   inline void mark_dirty(syncable::MetahandleSet* dirty_index) {
     if (!dirty_ && dirty_index) {
       DCHECK_NE(0, ref(META_HANDLE));
       dirty_index->insert(ref(META_HANDLE));
     }
     dirty_ = true;
+    memory_usage_ = kMemoryUsageUnknown;
   }
 
   // Clear the dirty bit, and optionally remove this entry's metahandle from
   // a provided index on dirty bits in |dirty_index|. Parameter may be null,
   // and will result only in clearing dirty bit of this entry.
   inline void clear_dirty(syncable::MetahandleSet* dirty_index) {
     if (dirty_ && dirty_index) {
       DCHECK_NE(0, ref(META_HANDLE));
       dirty_index->erase(ref(META_HANDLE));
     }
@@ skipping 132 matching lines @@
   bool ShouldMaintainPosition() const;
   bool ShouldMaintainHierarchy() const;
 
   // Dumps all kernel info into a DictionaryValue and returns it.
   // Transfers ownership of the DictionaryValue to the caller.
   // Note: |cryptographer| is an optional parameter for use in decrypting
   // encrypted specifics. If it is null or the specifics are not decryptsble,
   // they will be serialized as empty proto's.
   base::DictionaryValue* ToValue(Cryptographer* cryptographer) const;
 
+  size_t EstimateMemoryUsage() const;
+
  private:
   // Tracks whether this entry needs to be saved to the database.
   bool dirty_;
+  mutable size_t memory_usage_;
+  constexpr static size_t kMemoryUsageUnknown = size_t(-1);
 };
 
 template <typename T>
 class EntryKernelLessByMetaHandle {
  public:
   inline bool operator()(T a, T b) const {
     return a->ref(META_HANDLE) < b->ref(META_HANDLE);
   }
 };
 
@@ skipping 19 matching lines @@
 
 std::unique_ptr<base::ListValue> EntryKernelMutationMapToValue(
     const EntryKernelMutationMap& mutations);
 
 std::ostream& operator<<(std::ostream& os, const EntryKernel& entry_kernel);
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_SYNCABLE_ENTRY_KERNEL_H_