Fix global dumps to be dumped only when shared memory is actually used

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..6621452d1830f2be4244041c80fa717030f7c3e3 100644
--- a/gpu/command_buffer/client/mapped_memory.cc
+++ b/gpu/command_buffer/client/mapped_memory.cc
@@ -186,11 +186,12 @@ 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);
+    if (chunk->buffer()->backing()->is_shared()) {
+      auto guid = GetBufferGUIDForTracing(tracing_process_id, chunk->shm_id());
+      const int kImportance = 2;
+      pmd->CreateSharedGlobalAllocatorDump(guid);
+      pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
+    }
   }
 
   return true;