[tracing] Switch to new heap dump format.

third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp

Index: third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
diff --git a/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp b/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
index baefa38a3657d96e2ca457172b38070de389e552..9840f30b71ead1f158c22af4fdc312450716b941 100644
--- a/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
+++ b/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
@@ -67,24 +67,8 @@ bool BlinkGCMemoryDumpProvider::OnMemoryDump(
   DumpMemoryTotals(memory_dump);
 
   if (is_heap_profiling_enabled_) {
-    // Overhead should always be reported, regardless of light vs. heavy.
-    base::trace_event::TraceEventMemoryOverhead overhead;
-    std::unordered_map<base::trace_event::AllocationContext,
-                       base::trace_event::AllocationMetrics>
-        metrics_by_context;
-    {
-      MutexLocker locker(allocation_register_mutex_);
-      if (level_of_detail == MemoryDumpLevelOfDetail::DETAILED) {
-        for (const auto& alloc_size : *allocation_register_) {
-          base::trace_event::AllocationMetrics& metrics =
-              metrics_by_context[alloc_size.context];
-          metrics.size += alloc_size.size;
-          metrics.count++;
-        }
-      }
-      allocation_register_->EstimateTraceMemoryOverhead(&overhead);
-    }
-    memory_dump->DumpHeapUsage(metrics_by_context, overhead, "blink_gc");
+    MutexLocker locker(allocation_register_mutex_);
+    memory_dump->DumpHeapUsage(*allocation_register_, "blink_gc");
   }
 
   // Merge all dumps collected by ThreadHeap::collectGarbage.