[tracing] Display the resident size of the discardable memory segments

base/trace_event/process_memory_dump.h

 // Copyright 2015 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 BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_
 #define BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_
 
 #include <vector>
 
 #include "base/base_export.h"
@@ skipping 102 matching lines @@
   // ProcessMemoryDump, transferring their ownership to this instance.
   // |other| will be an empty ProcessMemoryDump after this method returns.
   // This is to allow dump providers to pre-populate ProcessMemoryDump instances
   // and later move their contents into the ProcessMemoryDump passed as argument
   // of the MemoryDumpProvider::OnMemoryDump(ProcessMemoryDump*) callback.
   void TakeAllDumpsFrom(ProcessMemoryDump* other);
 
   // Called at trace generation time to populate the TracedValue.
   void AsValueInto(TracedValue* value) const;
 
+  // Returns the total bytes resident for a memory segment, with given
+  // |start_address| and |mapped_size|. |mapped_size| is specified in bytes. The
+  // value returned is valid only if the given range is currently mmapped by the
+  // process. Returns -1 if counting is not implemented in the current platform.
+  static ssize_t CountResidentBytes(void* start_address, size_t mapped_size);

[Primiano Tucci (use gerrit), 2015/10/06 17:14:09]

IIRC static methods should be declared before non statics. Move this up.

[ssid, 2015/10/07 09:13:19]

Done.

+
   ProcessMemoryTotals* process_totals() { return &process_totals_; }
   bool has_process_totals() const { return has_process_totals_; }
   void set_has_process_totals() { has_process_totals_ = true; }
 
   ProcessMemoryMaps* process_mmaps() { return &process_mmaps_; }
   bool has_process_mmaps() const { return has_process_mmaps_; }
   void set_has_process_mmaps() { has_process_mmaps_ = true; }
 
  private:
   void AddAllocatorDumpInternal(MemoryAllocatorDump* mad);
@@ skipping 15 matching lines @@
   // Keeps track of relationships between MemoryAllocatorDump(s).
   std::vector<MemoryAllocatorDumpEdge> allocator_dumps_edges_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMemoryDump);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_