Add support to create memory allocator dump in base::DiscardableMemory

content/common/discardable_shared_memory_heap.h

Index: content/common/discardable_shared_memory_heap.h
diff --git a/content/common/discardable_shared_memory_heap.h b/content/common/discardable_shared_memory_heap.h
index 7ded677c3cc75630b61181c16a4b20258943550e..63f685cbb356385ae001515332da8f83cae8ea73 100644
--- a/content/common/discardable_shared_memory_heap.h
+++ b/content/common/discardable_shared_memory_heap.h
@@ -94,6 +94,13 @@ class CONTENT_EXPORT DiscardableSharedMemoryHeap {
       uint64 tracing_process_id,
       int32 segment_id);
 
+  // Returns a MemoryAllocatorDump for a given span on |pmd| with the size of
+  // the span.
+  base::trace_event::MemoryAllocatorDump* CreateMemoryAllocatorDump(
+      Span* span,
+      const char* name,
+      base::trace_event::ProcessMemoryDump* pmd) const;
+
  private:
   class ScopedMemorySegment {
    public:
@@ -107,6 +114,11 @@ class CONTENT_EXPORT DiscardableSharedMemoryHeap {
     bool IsUsed() const;
     bool IsResident() const;
 
+    base::trace_event::MemoryAllocatorDump* CreateMemoryAllocatorDump(
+        Span* span,
+        const char* name,
+        base::trace_event::ProcessMemoryDump* pmd) const;
+
     // Used for dumping memory statistics from the segment to chrome://tracing.
     void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd) const;