Adding discardable memory dump provider.

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 23b9cfb87d237dc1a4016dc029a0086aaf05fca1..cb7282a2019117a28a21d64a22b862be51e2ebf7 100644
--- a/content/common/discardable_shared_memory_heap.h
+++ b/content/common/discardable_shared_memory_heap.h
@@ -10,6 +10,7 @@
 #include "base/containers/linked_list.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
+#include "base/trace_event/process_memory_dump.h"
 #include "content/common/content_export.h"
 
 namespace base {
@@ -17,6 +18,7 @@ class DiscardableSharedMemory;
 }
 
 namespace content {
+typedef int32_t DiscardableSharedMemoryId;
 
 // Implements a heap of discardable shared memory. An array of free lists
 // is used to keep track of free blocks.
@@ -83,22 +85,29 @@ class CONTENT_EXPORT DiscardableSharedMemoryHeap {
   // Returns bytes of memory currently in the free lists.
   size_t GetSizeOfFreeLists() const;
 
+  // Dumps memory statistics for chrome://tracing.
+  bool DumpMemoryStatisticsInto(base::trace_event::ProcessMemoryDump* pmd);
+
  private:
   class ScopedMemorySegment {
    public:
     ScopedMemorySegment(DiscardableSharedMemoryHeap* heap,
                         scoped_ptr<base::DiscardableSharedMemory> shared_memory,
                         size_t size,
+                        DiscardableSharedMemoryId id,
                         const base::Closure& deleted_callback);
     ~ScopedMemorySegment();
 
     bool IsUsed() const;
     bool IsResident() const;
+    void DumpMemoryStatisticsInto(

[reveman, 2015/04/27 13:28:11]

nit: maybe use the same name as MemoryDumpProvider (just "DumpInto") so we
remember to keep this consistent in case MemoryDumpProvider change..

[ssid, 2015/04/27 14:27:01]

Done.

+        base::trace_event::ProcessMemoryDump* pmd) const;
 
    private:
     DiscardableSharedMemoryHeap* const heap_;
     scoped_ptr<base::DiscardableSharedMemory> shared_memory_;
     const size_t size_;
+    const DiscardableSharedMemoryId id_;
     const base::Closure deleted_callback_;
 
     DISALLOW_COPY_AND_ASSIGN(ScopedMemorySegment);
@@ -114,6 +123,10 @@ class CONTENT_EXPORT DiscardableSharedMemoryHeap {
   bool IsMemoryResident(const base::DiscardableSharedMemory* shared_memory);
   void ReleaseMemory(const base::DiscardableSharedMemory* shared_memory,
                      size_t size);
+  void DumpSegmentStatistics(const base::DiscardableSharedMemory* shared_memory,

[reveman, 2015/04/27 13:28:11]

nit: same here, maybe keep this consistent: DumpInto

[ssid, 2015/04/27 14:27:01]

Done.

+                             size_t segment_size,
+                             DiscardableSharedMemoryId id,
+                             base::trace_event::ProcessMemoryDump* pmd);
 
   size_t block_size_;
   size_t num_blocks_;