[tracing] Track number of allocations in heap profiler

third_party/WebKit/Source/platform/PartitionAllocMemoryDumpProvider.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/PartitionAllocMemoryDumpProvider.h"
 
 #include "base/trace_event/heap_profiler_allocation_context.h"
 #include "base/trace_event/heap_profiler_allocation_context_tracker.h"
 #include "base/trace_event/heap_profiler_allocation_register.h"
 #include "base/trace_event/process_memory_dump.h"
@@ skipping 94 matching lines @@
 {
     DEFINE_STATIC_LOCAL(PartitionAllocMemoryDumpProvider, instance, ());
     return &instance;
 }
 
 bool PartitionAllocMemoryDumpProvider::onMemoryDump(WebMemoryDumpLevelOfDetail levelOfDetail, WebProcessMemoryDump* 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, size_t> bytesByContext;
+        base::hash_map<base::trace_event::AllocationContext, base::trace_event::AllocationMetrics> metricsByContext;
         {
             MutexLocker locker(m_allocationRegisterMutex);
             // Dump only the overhead estimation in non-detailed dumps.
             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, "partition_alloc");
+        memoryDump->dumpHeapUsage(metricsByContext, overhead, "partition_alloc");
     }
 
     PartitionStatsDumperImpl partitionStatsDumper(memoryDump, levelOfDetail);
 
     WebMemoryAllocatorDump* partitionsDump = memoryDump->createMemoryAllocatorDump(
         String::format("%s/%s", kPartitionAllocDumpName, kPartitionsDumpName));
 
     // This method calls memoryStats.partitionsDumpBucketStats with memory statistics.
     WTF::Partitions::dumpMemoryStats(levelOfDetail == WebMemoryDumpLevelOfDetail::Light, &partitionStatsDumper);
 
@@ skipping 42 matching lines @@
 }
 
 void PartitionAllocMemoryDumpProvider::remove(void* address)
 {
     MutexLocker locker(m_allocationRegisterMutex);
     if (m_allocationRegister)
         m_allocationRegister->Remove(address);
 }
 
 } // namespace blink