[WIP] Add SharedMemoryTracker to dump base::SharedMemory usage

components/discardable_memory/common/discardable_shared_memory_heap.h

 // Copyright 2014 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 COMPONENTS_DISCARDABLE_MEMORY_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_
 #define COMPONENTS_DISCARDABLE_MEMORY_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 78 matching lines @@
 
   // Returns total bytes of memory in heap.
   size_t GetSize() const;
 
   // Returns bytes of memory currently in the free lists.
   size_t GetSizeOfFreeLists() const;
 
   // Dumps memory statistics for chrome://tracing.
   bool OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd);
 
-  // Returns a unique identifier for a given tuple of (process id, segment id)
-  // that can be used to match memory dumps across different processes.
-  static base::trace_event::MemoryAllocatorDumpGuid GetSegmentGUIDForTracing(
-      uint64_t tracing_process_id,
-      int32_t 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:
@@ skipping 62 matching lines @@
   // is a free list of runs that consist of k blocks. The 256th entry is a
   // free list of runs that have length >= 256 blocks.
   base::LinkedList<Span> free_spans_[256];
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableSharedMemoryHeap);
 };
 
 }  // namespace discardable_memory
 
 #endif  // COMPONENTS_DISCARDABLE_MEMORY_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_