[tracing] Switch to new heap dump format.

base/trace_event/process_memory_dump.cc

Index: base/trace_event/process_memory_dump.cc
diff --git a/base/trace_event/process_memory_dump.cc b/base/trace_event/process_memory_dump.cc
index 63d1340e42e3222c3ee99e92a7e676279cffb8a1..45a3c038f1de08dc9932a97b271b2889301747df 100644
--- a/base/trace_event/process_memory_dump.cc
+++ b/base/trace_event/process_memory_dump.cc
@@ -11,7 +11,8 @@
 #include "base/memory/ptr_util.h"
 #include "base/process/process_metrics.h"
 #include "base/strings/stringprintf.h"
-#include "base/trace_event/heap_profiler_heap_dump_writer.h"
+#include "base/trace_event/heap_profiler_allocation_register.h"
+#include "base/trace_event/heap_profiler_event_writer.h"
 #include "base/trace_event/memory_infra_background_whitelist.h"
 #include "base/trace_event/process_memory_totals.h"
 #include "base/trace_event/trace_event_argument.h"
@@ -239,17 +240,18 @@ MemoryAllocatorDump* ProcessMemoryDump::GetSharedGlobalAllocatorDump(
 }
 
 void ProcessMemoryDump::DumpHeapUsage(
-    const base::hash_map<base::trace_event::AllocationContext,
-        base::trace_event::AllocationMetrics>& metrics_by_context,
-    base::trace_event::TraceEventMemoryOverhead& overhead,
+    const AllocationRegister& allocation_register,
     const char* allocator_name) {
-  if (!metrics_by_context.empty()) {
+  if (dump_args_.level_of_detail == MemoryDumpLevelOfDetail::DETAILED &&
+      allocation_register.begin() != allocation_register.end()) {
     DCHECK_EQ(0ul, heap_dumps_.count(allocator_name));
-    std::unique_ptr<TracedValue> heap_dump = ExportHeapDump(
-        metrics_by_context, *session_state());
+    std::unique_ptr<TracedValue> heap_dump =
+        SerializeHeapDump(allocation_register, *session_state());
     heap_dumps_[allocator_name] = std::move(heap_dump);
   }
 
+  TraceEventMemoryOverhead overhead;
+  allocation_register.EstimateTraceMemoryOverhead(&overhead);
   std::string base_name = base::StringPrintf("tracing/heap_profiler_%s",
                                              allocator_name);
   overhead.DumpInto(base_name.c_str(), this);
@@ -314,10 +316,9 @@ void ProcessMemoryDump::AsValueInto(TracedValue* value) const {
   }
 
   if (heap_dumps_.size() > 0) {
-    value->BeginDictionary("heaps");
-    for (const auto& name_and_dump : heap_dumps_)
-      value->SetValueWithCopiedName(name_and_dump.first, *name_and_dump.second);
-    value->EndDictionary();  // "heaps"
+    auto profile_data =
+        SerializeHeapProfileEventData(heap_dumps_, *session_state_);
+    value->SetValue("heaps_v2", *profile_data);
   }
 
   value->BeginArray("allocators_graph");