Implement the renderer side of the mojo based local storage implementation.

content/renderer/dom_storage/local_storage_cached_areas.h

Index: content/renderer/dom_storage/local_storage_cached_areas.h
diff --git a/content/renderer/dom_storage/local_storage_cached_areas.h b/content/renderer/dom_storage/local_storage_cached_areas.h
index fba1daa4eed32c195a97dd05ca634c6773dc3c08..e9a292c75633b8ea9db5079fe2a05224fc33dfd2 100644
--- a/content/renderer/dom_storage/local_storage_cached_areas.h
+++ b/content/renderer/dom_storage/local_storage_cached_areas.h
@@ -8,7 +8,6 @@
 #include <map>
 
 #include "base/macros.h"
-#include "base/memory/ref_counted.h"
 #include "url/origin.h"
 
 namespace content {
@@ -25,8 +24,10 @@ class LocalStorageCachedAreas {
       StoragePartitionService* storage_partition_service);
   ~LocalStorageCachedAreas();
 
-  scoped_refptr<LocalStorageCachedArea> GetLocalStorageCachedArea(
-      const url::Origin& origin);
+  // Returns, creating if necessary, a cached storage area for the given origin.
+  // The object owns itself, and self-destructs when there no storage areas for
+  // the origin left.
+  LocalStorageCachedArea* GetLocalStorageCachedArea(const url::Origin& origin);

[michaeln, 2016/03/18 01:05:17]

naming nit: since these are in a class named LocalStorageCachedAreas, you could
use shorter method names... maybe OpenCachedArea/CacheAreaClosed()

[jam, 2016/03/18 16:48:33]

Done.

 
   // Called by LocalStorageCachedArea on destruction.
   void LocalStorageCacheAreaClosed(LocalStorageCachedArea* cached_area);