PartitionAllocMemoryDumpProvider can directly inherit from MemoryDumpProvider

base/trace_event/process_memory_dump.h

Index: base/trace_event/process_memory_dump.h
diff --git a/base/trace_event/process_memory_dump.h b/base/trace_event/process_memory_dump.h
index 5ac14fea939a53be452481cca2ab90ea50ac79cb..7f99c9823ee73841c9ebae9f99348bd4b5965e86 100644
--- a/base/trace_event/process_memory_dump.h
+++ b/base/trace_event/process_memory_dump.h
@@ -122,6 +122,13 @@ class BASE_EXPORT ProcessMemoryDump {
   void AddHeapDump(const std::string& absolute_name,

[Primiano Tucci (use gerrit), 2016/04/22 13:05:57]

at this point we can remove this, right?

[bashi, 2016/04/24 23:33:12]

BlinkGCMemoryDumpProvider uses it indirectly. Added a TODO.

                    std::unique_ptr<TracedValue> heap_dump);
 
+  // Dumps heap usage.
+  void DumpHeapUsage(const base::hash_map<base::trace_event::AllocationContext,
+                                          base::trace_event::AllocationMetrics>&
+                         metrics_by_context,
+                     base::trace_event::TraceEventMemoryOverhead& overhead,
+                     const char* allocator_name);
+
   // Adds an ownership relationship between two MemoryAllocatorDump(s) with the
   // semantics: |source| owns |target|, and has the effect of attributing
   // the memory usage of |target| to |source|. |importance| is optional and