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

gpu/command_buffer/client/cmd_buffer_helper.cc

Index: gpu/command_buffer/client/cmd_buffer_helper.cc
diff --git a/gpu/command_buffer/client/cmd_buffer_helper.cc b/gpu/command_buffer/client/cmd_buffer_helper.cc
index 7021fa399f4ccf7f887667ab73589d5753206b43..b1e6eade49cd2855a955c63859c0e97574bb619a 100644
--- a/gpu/command_buffer/client/cmd_buffer_helper.cc
+++ b/gpu/command_buffer/client/cmd_buffer_helper.cc
@@ -10,6 +10,7 @@
 
 #include <algorithm>
 #include "base/logging.h"
+#include "base/memory/shared_memory_tracker.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
@@ -377,10 +378,15 @@ bool CommandBufferHelper::OnMemoryDump(
     dump->AddScalar(
         "free_size", MemoryAllocatorDump::kUnitsBytes,
         GetTotalFreeEntriesNoWaiting() * sizeof(CommandBufferEntry));
-    auto guid = GetBufferGUIDForTracing(tracing_process_id, ring_buffer_id_);
-    const int kImportance = 2;
-    pmd->CreateSharedGlobalAllocatorDump(guid);
-    pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
+    auto shared_memory = ring_buffer_->backing()->shared_memory();
+    if (shared_memory) {
+      auto guid = GetBufferGUIDForTracing(tracing_process_id, ring_buffer_id_);
+      const int kImportance = 2;
+      pmd->CreateSharedGlobalAllocatorDump(guid);
+      pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
+      base::SharedMemoryTracker::AddOwnershipEdgeToSharedGlobalDump(pmd, guid,
+          shared_memory->handle(), shared_memory->mapped_size());
+    }
   }
 
   return true;