[WIP] Add SharedMemoryTracker to dump base::SharedMemory usage

gpu/command_buffer/client/mapped_memory.cc

Index: gpu/command_buffer/client/mapped_memory.cc
diff --git a/gpu/command_buffer/client/mapped_memory.cc b/gpu/command_buffer/client/mapped_memory.cc
index 708e121f39c0c24a9593b0714bb14f3b28b5c210..ad1809cdc6d4fb01d6fba4280e2a2bf1373a0c1c 100644
--- a/gpu/command_buffer/client/mapped_memory.cc
+++ b/gpu/command_buffer/client/mapped_memory.cc
@@ -13,6 +13,7 @@
 #include "base/atomic_sequence_num.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#include "base/memory/shared_memory_tracker.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/memory_dump_manager.h"
@@ -173,9 +174,6 @@ bool MappedMemoryManager::OnMemoryDump(
     return true;
   }
 
-  const uint64_t tracing_process_id =
-      base::trace_event::MemoryDumpManager::GetInstance()
-          ->GetTracingProcessId();
   for (const auto& chunk : chunks_) {
     std::string dump_name = base::StringPrintf(
         "gpu/mapped_memory/manager_%d/chunk_%d", tracing_id_, chunk->shm_id());
@@ -186,11 +184,19 @@ bool MappedMemoryManager::OnMemoryDump(
     dump->AddScalar("free_size", MemoryAllocatorDump::kUnitsBytes,
                     chunk->GetFreeSize());
 
-    auto guid = GetBufferGUIDForTracing(tracing_process_id, chunk->shm_id());
-
-    const int kImportance = 2;
-    pmd->CreateSharedGlobalAllocatorDump(guid);
-    pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
+    auto* shared_memory = chunk->buffer()->backing()->shared_memory();
+    if (shared_memory) {
+      base::SharedMemoryTracker::AddOwnershipEdges(pmd, dump->guid(),
+                                                   *shared_memory);
+    } else {
+      const uint64_t tracing_process_id =
+          base::trace_event::MemoryDumpManager::GetInstance()
+              ->GetTracingProcessId();
+      auto guid = GetBufferGUIDForTracing(tracing_process_id, chunk->shm_id());
+      const int kImportance = 2;
+      pmd->CreateSharedGlobalAllocatorDump(guid);
+      pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
+    }
   }
 
   return true;