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

gpu/command_buffer/service/buffer_manager.cc

Index: gpu/command_buffer/service/buffer_manager.cc
diff --git a/gpu/command_buffer/service/buffer_manager.cc b/gpu/command_buffer/service/buffer_manager.cc
index 4469af8f2edde71928f86ee080007303eda04c91..056f6540b0ea01c66c522dd41499a4a0c89e05fe 100644
--- a/gpu/command_buffer/service/buffer_manager.cc
+++ b/gpu/command_buffer/service/buffer_manager.cc
@@ -10,6 +10,7 @@
 
 #include "base/format_macros.h"
 #include "base/logging.h"
+#include "base/memory/shared_memory_tracker.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -737,10 +738,18 @@ bool BufferManager::OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                     MemoryAllocatorDump::kUnitsBytes,
                     static_cast<uint64_t>(buffer->size()));
 
-    auto guid = gl::GetGLBufferGUIDForTracing(share_group_tracing_guid,
-                                              client_buffer_id);
-    pmd->CreateSharedGlobalAllocatorDump(guid);
-    pmd->AddOwnershipEdge(dump->guid(), guid);
+    auto mapped_range = buffer->GetMappedRange();
+    if (!mapped_range)
+      continue;
+    auto shared_memory = mapped_range->shm->backing()->shared_memory();
+    if (shared_memory) {
+      auto guid = gl::GetGLBufferGUIDForTracing(share_group_tracing_guid,
+                                                client_buffer_id);
+      pmd->CreateSharedGlobalAllocatorDump(guid);
+      pmd->AddOwnershipEdge(dump->guid(), guid);
+      base::SharedMemoryTracker::AddOwnershipEdgeToSharedGlobalDump(pmd, guid,
+          shared_memory->handle(), shared_memory->mapped_size());
+    }
   }
 
   return true;