[IndexedDB] Adding txn, value, and key size metrics

third_party/WebKit/Source/modules/indexeddb/IDBObjectStore.cpp

Index: third_party/WebKit/Source/modules/indexeddb/IDBObjectStore.cpp
diff --git a/third_party/WebKit/Source/modules/indexeddb/IDBObjectStore.cpp b/third_party/WebKit/Source/modules/indexeddb/IDBObjectStore.cpp
index e799703de7fdd455cf1246e44287fb97eba5a2ee..ebe882f762fd9791512e60d1043ed8a3d323af2b 100644
--- a/third_party/WebKit/Source/modules/indexeddb/IDBObjectStore.cpp
+++ b/third_party/WebKit/Source/modules/indexeddb/IDBObjectStore.cpp
@@ -511,6 +511,9 @@ IDBRequest* IDBObjectStore::put(ScriptState* script_state,
   serialized_value->ToWireBytes(wire_bytes);
   RefPtr<SharedBuffer> value_buffer = SharedBuffer::AdoptVector(wire_bytes);
 
+  UMA_HISTOGRAM_MEMORY_KB("WebCore.IndexedDB.PutValueSize",
+                          value_buffer->size() / 1024);
+
   request->StorePutOperationBlobs(serialized_value->BlobDataHandles());
 
   BackendDB()->Put(transaction_->Id(), Id(), WebData(value_buffer), blob_info,