Track SimpleCache memory usage in net/ MemoryDumpProvider

net/disk_cache/disk_cache.h

 // Copyright (c) 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.
 
 // Defines the public interface of the disk cache. For more details see
 // http://dev.chromium.org/developers/design-documents/network-stack/disk-cache
 
 #ifndef NET_DISK_CACHE_DISK_CACHE_H_
 #define NET_DISK_CACHE_DISK_CACHE_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "base/strings/string_split.h"
 #include "base/time/time.h"
 #include "net/base/cache_type.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_export.h"
 
 namespace base {
 class FilePath;
 class SingleThreadTaskRunner;
+namespace trace_event {
+class ProcessMemoryDump;
+}
 }
 
 namespace net {
 class IOBuffer;
 class NetLog;
 }
 
 namespace disk_cache {
 
 class Entry;
@@ skipping 129 matching lines @@
   // Returns an iterator which will enumerate all entries of the cache in an
   // undefined order.
   virtual std::unique_ptr<Iterator> CreateIterator() = 0;
 
   // Return a list of cache statistics.
   virtual void GetStats(base::StringPairs* stats) = 0;
 
   // Called whenever an external cache in the system reuses the resource
   // referred to by |key|.
   virtual void OnExternalCacheHit(const std::string& key) = 0;
+
+  // Dumps memory allocation stats. |parent_dump_absolute_name| is the name
+  // used by the parent MemoryAllocatorDump in the memory dump hierarchy.
+  // TODO(xunjieli): Investigate memory usage from backends other than
+  // SimpleCache.

[ssid, 2017/02/01 02:45:48]

Slightly weird place to have this TODO about implementation at the interface. I
would suggest making this pure virtual and having TODO in the actual classes.

[xunjieli, 2017/02/01 14:55:18]

Done.

+  virtual void DumpMemoryStats(base::trace_event::ProcessMemoryDump* pmd,
+                               const std::string& parent_absolute_name) const {}
 };
 
 // This interface represents an entry in the disk cache.
 class NET_EXPORT Entry {
  public:
   typedef net::CompletionCallback CompletionCallback;
   typedef net::IOBuffer IOBuffer;
 
   // Marks this cache entry for deletion.
   virtual void Doom() = 0;
@@ skipping 156 matching lines @@
     entry->Close();
   }
 };
 
 // Automatically closes an entry when it goes out of scope.
 typedef std::unique_ptr<Entry, EntryDeleter> ScopedEntryPtr;
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_DISK_CACHE_H_