[IndexedDB] Pool and evict leveldb iterators, to save memory

content/browser/indexed_db/leveldb/leveldb_iterator.h

Index: content/browser/indexed_db/leveldb/leveldb_iterator.h
diff --git a/content/browser/indexed_db/leveldb/leveldb_iterator.h b/content/browser/indexed_db/leveldb/leveldb_iterator.h
index d5efa4bf51951f6218d0cbcb804e282c6397b4d2..ab62b81c6de2e9971d2c27e0923421921f69348a 100644
--- a/content/browser/indexed_db/leveldb/leveldb_iterator.h
+++ b/content/browser/indexed_db/leveldb/leveldb_iterator.h
@@ -21,6 +21,7 @@ class CONTENT_EXPORT LevelDBIterator {
   virtual leveldb::Status Prev() = 0;
   virtual base::StringPiece Key() const = 0;
   virtual base::StringPiece Value() const = 0;
+  virtual void EvictWorkingMemory(){};

[jsbell, 2017/03/21 00:15:48]

I seem to recall that there's a more common name for this operation that the
memory folks have plumbed through in various areas. We should try and conform
(unless I'm misremembering)

[dmurph, 2017/03/21 20:13:26]

I found memory pressure?
https://cs.chromium.org/chromium/src/base/memory/memory_pressure_listener.h?d...

So to avoid importing that enum - OnMemoryPressure()?

[jsbell, 2017/03/21 20:51:39]

I think PurgeMemory() is what I was looking for - that term seems to be used in
a bunch of places.

[dmurph, 2017/03/22 18:35:58]

Done.

 };
 
 }  // namespace content