[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 183 matching lines @@
       // 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.
       const uint64 child_tracing_process_id =
           ChildProcessHostImpl::ChildProcessUniqueIdToTracingProcessId(
               child_process_id);
       base::trace_event::MemoryAllocatorDumpGuid shared_segment_guid =
           DiscardableSharedMemoryHeap::GetSegmentGUIDForTracing(
               child_tracing_process_id, segment_id);
-      pmd->CreateSharedGlobalAllocatorDump(shared_segment_guid);
+      base::trace_event::MemoryAllocatorDump* global_dump =
+          pmd->CreateSharedGlobalAllocatorDump(shared_segment_guid);
       pmd->AddOwnershipEdge(dump->guid(), shared_segment_guid);
+
+#if defined(COUNT_RESIDENT_BYTES_SUPPORTED)
+      if (args.level_of_detail ==
+          base::trace_event::MemoryDumpLevelOfDetail::DETAILED) {
+        size_t resident_size =
+            base::trace_event::ProcessMemoryDump::CountResidentBytes(
+                segment->memory()->memory(), segment->memory()->mapped_size());
+
+        // This is added to the global dump since it has to be attributed to
+        // both the allocator dumps involved.
+        global_dump->AddScalar(
+            "resident_size",
+            base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+            static_cast<uint64>(resident_size));
+      }
+#endif  // defined(COUNT_RESIDENT_BYTES_SUPPORTED)
     }
   }
   return true;
 }
 
 void HostDiscardableSharedMemoryManager::
     AllocateLockedDiscardableSharedMemoryForChild(
         base::ProcessHandle process_handle,
         int child_process_id,
         size_t size,
@@ skipping 257 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