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

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 75d616a9b2eb44f41dbaf75a8fb5077a4b72f307..dbfc3beedd335a59753d4bbcfced1e88b0da860a 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -19,6 +19,7 @@
 #include <string>
 #include "base/atomic_sequence_num.h"
 #include "base/compiler_specific.h"
+#include "base/memory/shared_memory_tracker.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/string_split.h"
 #include "base/strings/stringprintf.h"
@@ -459,11 +460,16 @@ bool GLES2Implementation::OnMemoryDump(
   if (args.level_of_detail != MemoryDumpLevelOfDetail::BACKGROUND) {
     dump->AddScalar("free_size", MemoryAllocatorDump::kUnitsBytes,
                     transfer_buffer_->GetFreeSize());
-    auto guid = GetBufferGUIDForTracing(tracing_process_id,
-                                        transfer_buffer_->GetShmId());
-    const int kImportance = 2;
-    pmd->CreateSharedGlobalAllocatorDump(guid);
-    pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
+    auto shared_memory = transfer_buffer_->GetSharedMemory();
+    if (shared_memory) {
+      auto guid = GetBufferGUIDForTracing(tracing_process_id,
+                                          transfer_buffer_->GetShmId());
+      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;