[tracing] Show the local storage databases under dom_storage

content/browser/dom_storage/dom_storage_database_adapter.h

Index: content/browser/dom_storage/dom_storage_database_adapter.h
diff --git a/content/browser/dom_storage/dom_storage_database_adapter.h b/content/browser/dom_storage/dom_storage_database_adapter.h
index 9068af21f9769dae0b8d629d4be696b02ba5b1c0..8efea8b0d4ad275f9b6458cfb22be11c0cd8db3c 100644
--- a/content/browser/dom_storage/dom_storage_database_adapter.h
+++ b/content/browser/dom_storage/dom_storage_database_adapter.h
@@ -9,9 +9,17 @@
 // the per-origin DOMStorageDatabases for localStorage and
 // SessionStorageDatabase which stores multiple origins.
 
+#include <string>
+
 #include "content/common/content_export.h"
 #include "content/common/dom_storage/dom_storage_types.h"
 
+namespace base {
+namespace trace_event {
+class ProcessMemoryDump;
+}
+}
+
 namespace content {
 
 class CONTENT_EXPORT DOMStorageDatabaseAdapter {
@@ -22,6 +30,9 @@ class CONTENT_EXPORT DOMStorageDatabaseAdapter {
       bool clear_all_first, const DOMStorageValuesMap& changes) = 0;
   virtual void DeleteFiles() {}
   virtual void Reset() {}
+  // Adds memory statistics to |pmd| object for tracing.
+  virtual void ReportMemoryUsage(base::trace_event::ProcessMemoryDump* pmd,
+                                 const std::string& name) {}
 };
 
 }  // namespace content