[tracing] Track number of allocations in heap profiler

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 eea1e747c6a08964d482adae8e10dee18a147253..a0f755685c84f7232c01a581cd68e62ee8fcce2a 100644
--- a/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
+++ b/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
@@ -64,16 +64,19 @@ bool BlinkGCMemoryDumpProvider::onMemoryDump(WebMemoryDumpLevelOfDetail levelOfD
     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, size_t> bytesByContext;
+        base::hash_map<base::trace_event::AllocationContext, base::trace_event::AllocationMetrics> metricsByContext;
         {
             MutexLocker locker(m_allocationRegisterMutex);
             if (levelOfDetail == WebMemoryDumpLevelOfDetail::Detailed) {
-                for (const auto& allocSize : *m_allocationRegister)
-                    bytesByContext[allocSize.context] += allocSize.size;
+                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(bytesByContext, overhead, "blink_gc");
+        memoryDump->dumpHeapUsage(metricsByContext, overhead, "blink_gc");
     }
 
     // Merge all dumps collected by ThreadHeap::collectGarbage.