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

content/common/host_discardable_shared_memory_manager.cc

Index: content/common/host_discardable_shared_memory_manager.cc
diff --git a/content/common/host_discardable_shared_memory_manager.cc b/content/common/host_discardable_shared_memory_manager.cc
index 7590c1f9bb4c6848f950a21da491494ab04ea0d8..c58e4e9f1238545ca9ecbc6bb51e616162ee3b37 100644
--- a/content/common/host_discardable_shared_memory_manager.cc
+++ b/content/common/host_discardable_shared_memory_manager.cc
@@ -64,8 +64,22 @@ class DiscardableMemoryImpl : public base::DiscardableMemory {
     return shared_memory_->memory();
   }
 
+  base::trace_event::MemoryAllocatorDump* CreateMemoryAllocatorDump(
+      const char* name,
+      base::trace_event::ProcessMemoryDump* pmd) override {
+    // The memory could have been purged, but we still create a dump with
+    // mapped_size. So, the size can be inaccurate.
+    base::trace_event::MemoryAllocatorDump* dump =
+        pmd->CreateAllocatorDump(name);
+    dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
+                    base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                    shared_memory_->mapped_size());
+    return dump;
+  }
+
  private:
   scoped_ptr<base::DiscardableSharedMemory> shared_memory_;
+  size_t size_;

[reveman, 2015/08/24 16:50:06]

is this needed?

   const base::Closure deleted_callback_;
   bool is_locked_;