[tracing] Track number of allocations in heap profiler

base/trace_event/heap_profiler_heap_dump_writer.h

 // 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.
 
 #ifndef BASE_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_
 #define BASE_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <set>
 
 #include "base/base_export.h"
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/trace_event/heap_profiler_allocation_context.h"
 
 namespace base {
 namespace trace_event {
 
 class StackFrameDeduplicator;
 class TracedValue;
 class TypeNameDeduplicator;
 
-// Aggregates |bytes_by_context|, recursively breaks down the heap, and returns
-// a traced value with an "entries" array that can be dumped in the trace log,
-// following the format described in https://goo.gl/KY7zVE. The number of
-// entries is kept reasonable because long tails are not included.
+// Aggregates |metrics_by_context|, recursively breaks down the heap, and
+// returns a traced value with an "entries" array that can be dumped in the
+// trace log, following the format described in https://goo.gl/KY7zVE. The
+// number of entries is kept reasonable because long tails are not included.
 BASE_EXPORT std::unique_ptr<TracedValue> ExportHeapDump(
-    const hash_map<AllocationContext, size_t>& bytes_by_context,
+    const hash_map<AllocationContext, AllocationsSizeAndCount>&
+        metrics_by_context,
     StackFrameDeduplicator* stack_frame_deduplicator,
     TypeNameDeduplicator* type_name_deduplicator);
 
 namespace internal {
 
 namespace {
 struct Bucket;
 }
 
 // An entry in the "entries" array as described in https://goo.gl/KY7zVE.
 struct BASE_EXPORT Entry {
   size_t size;
+  size_t count;
 
   // References a backtrace in the stack frame deduplicator. -1 means empty
   // backtrace (the root of the tree).
   int stack_frame_id;
 
   // References a type name in the type name deduplicator. -1 indicates that
   // the size is the cumulative size for all types (the root of the tree).
   int type_id;
 };
 
@@ skipping 14 matching lines @@
   HeapDumpWriter(StackFrameDeduplicator* stack_frame_deduplicator,
                  TypeNameDeduplicator* type_name_deduplicator);
 
   ~HeapDumpWriter();
 
   // Aggregates allocations to compute the total size of the heap, then breaks
   // down the heap recursively. This produces the values that should be dumped
   // in the "entries" array. The number of entries is kept reasonable because
   // long tails are not included. Use |Serialize| to convert to a traced value.
   const std::set<Entry>& Summarize(
-      const hash_map<AllocationContext, size_t>& bytes_by_context);
+      const hash_map<AllocationContext, AllocationsSizeAndCount>&
+          metrics_by_context);
 
  private:
   // Inserts an |Entry| for |Bucket| into |entries_|. Returns false if the
   // entry was present before, true if it was not.
   bool AddEntryForBucket(const Bucket& bucket);
 
   // Recursively breaks down a bucket into smaller buckets and adds entries for
   // the buckets worth dumping to |entries_|.
   void BreakDown(const Bucket& bucket);
 
   // The collection of entries that is filled by |Summarize|.
   std::set<Entry> entries_;
 
   // Helper for generating the |stackFrames| dictionary. Not owned, must outlive
   // this heap dump writer instance.
   StackFrameDeduplicator* const stack_frame_deduplicator_;
 
   // Helper for converting type names to IDs. Not owned, must outlive this heap
   // dump writer instance.
   TypeNameDeduplicator* const type_name_deduplicator_;
 
   DISALLOW_COPY_AND_ASSIGN(HeapDumpWriter);
 };
 
 }  // namespace internal
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_