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

content/common/host_discardable_shared_memory_manager.cc

 // Copyright 2014 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.
 
 #include "content/common/host_discardable_shared_memory_manager.h"
 
 #include <algorithm>
 
 #include "base/atomic_sequence_num.h"
 #include "base/bind.h"
@@ skipping 167 matching lines @@
       const MemorySegment* segment = segment_entry.second.get();
       std::string dump_name = base::StringPrintf(
           "discardable/process_%x/segment_%d", child_process_id, segment_id);
       base::trace_event::MemoryAllocatorDump* dump =
           pmd->CreateAllocatorDump(dump_name);
 
       dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
                       base::trace_event::MemoryAllocatorDump::kUnitsBytes,
                       segment->memory()->mapped_size());
 
+      ssize_t resident_size =
+          base::trace_event::ProcessMemoryDump::CountResidentBytes(
+              segment->memory()->memory(), segment->memory()->mapped_size());
+      if (resident_size >= 0) {
+        dump->AddScalar("resident_size",
+                        base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                        static_cast<uint64>(resident_size));
+      }
+
       // Host can only tell if whole segment is locked or not.
       dump->AddScalar(
           "locked_size", base::trace_event::MemoryAllocatorDump::kUnitsBytes,
           segment->memory()->IsMemoryLocked() ? segment->memory()->mapped_size()
                                               : 0u);
 
       // Create the cross-process ownership edge. If the child creates a
       // corresponding dump for the same segment, this will avoid to
       // double-count them in tracing. If, instead, no other process will emit a
       // dump with the same guid, the segment will be accounted to the browser.
@@ skipping 275 matching lines @@
 
   enforce_memory_policy_pending_ = true;
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&HostDiscardableSharedMemoryManager::EnforceMemoryPolicy,
                  weak_ptr_factory_.GetWeakPtr()),
       base::TimeDelta::FromMilliseconds(kEnforceMemoryPolicyDelayMs));
 }
 
 }  // namespace content