[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 65ef5dee4f06439b05f7b8ab8dcdd65af40863d2..426b34d4b24f99a201a4f3b276e4479968a47ba0 100644
--- a/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
+++ b/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
@@ -64,24 +64,8 @@ bool BlinkGCMemoryDumpProvider::OnMemoryDump(
   dumpMemoryTotals(memoryDump);
 
   if (m_isHeapProfilingEnabled) {
-    // Overhead should always be reported, regardless of light vs. heavy.
-    base::trace_event::TraceEventMemoryOverhead overhead;
-    base::hash_map<base::trace_event::AllocationContext,
-                   base::trace_event::AllocationMetrics>
-        metricsByContext;
-    {
-      MutexLocker locker(m_allocationRegisterMutex);
-      if (levelOfDetail == MemoryDumpLevelOfDetail::DETAILED) {
-        for (const auto& allocSize : *m_allocationRegister) {
-          base::trace_event::AllocationMetrics& metrics =
-              metricsByContext[allocSize.context];
-          metrics.size += allocSize.size;
-          metrics.count++;
-        }
-      }
-      m_allocationRegister->EstimateTraceMemoryOverhead(&overhead);
-    }
-    memoryDump->DumpHeapUsage(metricsByContext, overhead, "blink_gc");
+    MutexLocker locker(m_allocationRegisterMutex);
+    memoryDump->DumpHeapUsage(*m_allocationRegister, "blink_gc");
   }
 
   // Merge all dumps collected by ThreadHeap::collectGarbage.