PartitionAllocMemoryDumpProvider can directly inherit from MemoryDumpProvider

base/trace_event/process_memory_dump.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_PROCESS_MEMORY_DUMP_H_
 #define BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_
 
 #include <stddef.h>
 
 #include <unordered_map>
@@ skipping 101 matching lines @@
   // Looks up a shared MemoryAllocatorDump given its guid.
   MemoryAllocatorDump* GetSharedGlobalAllocatorDump(
       const MemoryAllocatorDumpGuid& guid) const;
 
   // Returns the map of the MemoryAllocatorDumps added to this dump.
   const AllocatorDumpsMap& allocator_dumps() const { return allocator_dumps_; }
 
   // Adds a heap dump for the allocator with |absolute_name|. The |TracedValue|
   // must have the correct format. |trace_event::HeapDumper| will generate such
   // a value from a |trace_event::AllocationRegister|.
   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
   // relevant only for the cases of co-ownership, where it acts as a z-index:
   // the owner with the highest importance will be attributed |target|'s memory.
   void AddOwnershipEdge(const MemoryAllocatorDumpGuid& source,
                         const MemoryAllocatorDumpGuid& target,
                         int importance);
   void AddOwnershipEdge(const MemoryAllocatorDumpGuid& source,
                         const MemoryAllocatorDumpGuid& target);
@@ skipping 58 matching lines @@
   // Keeps track of relationships between MemoryAllocatorDump(s).
   std::vector<MemoryAllocatorDumpEdge> allocator_dumps_edges_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMemoryDump);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_