[tracing] Simplify design of MemoryAllocatorDump

base/trace_event/memory_allocator_dump.h

Index: base/trace_event/memory_allocator_dump.h
diff --git a/base/trace_event/memory_allocator_dump.h b/base/trace_event/memory_allocator_dump.h
index 4d7293e710f5ef19f591ae4cdb8d3b712a3ac3f0..1c786ab032ccba06fc3bba14baab9aee1fa63526 100644
--- a/base/trace_event/memory_allocator_dump.h
+++ b/base/trace_event/memory_allocator_dump.h
@@ -8,54 +8,92 @@
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/logging.h"
-#include "base/trace_event/memory_allocator_attributes.h"
+#include "base/trace_event/memory_allocator_attributes_type_info.h"
 #include "base/values.h"
 
 namespace base {
 namespace trace_event {
 
 class MemoryDumpManager;
+class ProcessMemoryDump;
 class TracedValue;
 
 // Data model for user-land memory allocator dumps.
 class BASE_EXPORT MemoryAllocatorDump {
  public:
-  MemoryAllocatorDump(const std::string& name, MemoryAllocatorDump* parent);
+  // Returns the absolute name for a given (|allocator_name|,|heap_name|) tuple.
+  static std::string GetAbsoluteName(const std::string& allocator_name,
+                                     const std::string& heap_name);
+
+  // Use as argument for |heap_name| when the allocator has only one root heap.
+  static const char kRootHeap[];
+
+  // MemoryAllocatorDump is owned by ProcessMemoryDump.
+  MemoryAllocatorDump(const std::string& allocator_name,
+                      const std::string& heap_name,
+                      ProcessMemoryDump* process_memory_dump);
   ~MemoryAllocatorDump();
 
-  const std::string& name() const { return name_; }
-  const MemoryAllocatorDump* parent() const { return parent_; }
+  // Name of the allocator, a plain string with no separators (e.g, "malloc").
+  const std::string& allocator_name() const { return allocator_name_; }
+
+  // Name of the heap being dumped, either: "heap", "heap/subheap" or kRootHeap
+  // if the allocator has just one root heap.
+  const std::string& heap_name() const { return heap_name_; }
+
+  // Absolute name, unique within the scope of an entire ProcessMemoryDump.
+  // In practice this is "allocator_name/heap/subheap".
+  std::string GetAbsoluteName() const;
+
+  // Inner size: Bytes requested by clients of the allocator, without accounting
+  // for any metadata or allocator-specific bookeeping structs.
+  void set_allocated_objects_size_in_bytes(uint64 value) {
+    allocated_objects_size_in_bytes_ = value;
+  }
+  uint64 allocated_objects_size_in_bytes() const {
+    return allocated_objects_size_in_bytes_;
+  }
 
+  // Outer size: bytes requested to the system to handle all the allocations,
+  // including any allocator-internal metadata / bookeeping structs. For
+  // instance, in the case of an allocator which gets pages to the system via
+  // mmap() or similar, this is the number of requested pages * 4k.
   void set_physical_size_in_bytes(uint64 value) {
     physical_size_in_bytes_ = value;
   }
   uint64 physical_size_in_bytes() const { return physical_size_in_bytes_; }
 
+  // Number of objects allocated, if known, or 0 if not available.
   void set_allocated_objects_count(uint64 value) {
     allocated_objects_count_ = value;
   }
   uint64 allocated_objects_count() const { return allocated_objects_count_; }
 
-  void set_allocated_objects_size_in_bytes(uint64 value) {
-    allocated_objects_size_in_bytes_ = value;
-  }
-  uint64 allocated_objects_size_in_bytes() const {
-    return allocated_objects_size_in_bytes_;
-  }
-
-  void SetExtraAttribute(const std::string& name, int value);
-  int GetExtraIntegerAttribute(const std::string& name) const;
+  // Get/Set extra attributes. The attributes name must have been previously
+  // declared through MemoryDumpProvider.DeclareAllocatorAttribute().
+  void SetAttribute(const std::string& name, int value);
+  int GetIntegerAttribute(const std::string& name) const;
 
   // Called at trace generation time to populate the TracedValue.
   void AsValueInto(TracedValue* value) const;
 
+  // Get the ProcessMemoryDump instance that owns this.
+  ProcessMemoryDump* process_memory_dump() const {
+    return process_memory_dump_;
+  }
+
+  // Retrieves the map of allocator attributes types, which is shared by all
+  // MemoryAllocatorDump(s) across all ProcessMemoryDump(s) per tracing session.
+  const MemoryAllocatorAttributesTypeInfo& GetAttributesTypeInfo() const;
+
  private:
-  const std::string name_;
-  MemoryAllocatorDump* const parent_;  // Not owned.
+  const std::string allocator_name_;
+  const std::string heap_name_;
+  ProcessMemoryDump* const process_memory_dump_;  // Not owned (PMD owns this).
   uint64 physical_size_in_bytes_;
   uint64 allocated_objects_count_;
   uint64 allocated_objects_size_in_bytes_;
-  DictionaryValue extra_attributes_;
+  DictionaryValue attributes_values_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryAllocatorDump);
 };