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

content/common/discardable_shared_memory_heap.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/discardable_shared_memory_heap.h"
 
 #include <algorithm>
 
 #include "base/format_macros.h"
 #include "base/memory/discardable_shared_memory.h"
@@ skipping 377 matching lines @@
   size_t locked_objects_size_in_bytes = locked_objects_blocks * block_size_;
 
   std::string segment_dump_name =
       base::StringPrintf("discardable/segment_%d", segment_id);
   base::trace_event::MemoryAllocatorDump* segment_dump =
       pmd->CreateAllocatorDump(segment_dump_name);
   segment_dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
                           base::trace_event::MemoryAllocatorDump::kUnitsBytes,
                           size);
 
+  ssize_t resident_size =
+      base::trace_event::ProcessMemoryDump::CountResidentBytes(
+          shared_memory->memory(), shared_memory->mapped_size());
+  if (resident_size >= 0) {
+    segment_dump->AddScalar("resident_size",
+                            base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                            static_cast<uint64>(resident_size));
+  }
+
   base::trace_event::MemoryAllocatorDump* obj_dump =
       pmd->CreateAllocatorDump(segment_dump_name + "/allocated_objects");
   obj_dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameObjectCount,
                       base::trace_event::MemoryAllocatorDump::kUnitsObjects,
                       allocated_objects_count);
   obj_dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
                       base::trace_event::MemoryAllocatorDump::kUnitsBytes,
                       allocated_objects_size_in_bytes);
   obj_dump->AddScalar("locked_size",
                       base::trace_event::MemoryAllocatorDump::kUnitsBytes,
@@ skipping 40 matching lines @@
   ScopedVector<ScopedMemorySegment>::const_iterator it =
       std::find_if(memory_segments_.begin(), memory_segments_.end(),
                    [span](const ScopedMemorySegment* segment) {
                      return segment->ContainsSpan(span);
                    });
   DCHECK(it != memory_segments_.end());
   return (*it)->CreateMemoryAllocatorDump(span, block_size_, name, pmd);
 }
 
 }  // namespace content