[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 e627183e10da1647abc245c42f10eb227950ecaa..1232a60afa9c1b504784603675f0759f8bc4b84a 100644
--- a/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
+++ b/third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
@@ -64,16 +64,18 @@ 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::AllocationsSizeAndCount> 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) {
+                    metricsByContext[allocSize.context].size += allocSize.size;
+                    metricsByContext[allocSize.context].count++;

[Dmitry Skiba, 2016/04/14 19:07:30]

Avoid second lookup.

[ssid, 2016/04/14 20:17:11]

Done.

+                }
             }
             m_allocationRegister->EstimateTraceMemoryOverhead(&overhead);
         }
-        memoryDump->dumpHeapUsage(bytesByContext, overhead, "blink_gc");
+        memoryDump->dumpHeapUsage(metricsByContext, overhead, "blink_gc");
     }
 
     // Merge all dumps collected by Heap::collectGarbage.