Add use counters to determine the fate of DOMStringList

Source/modules/indexeddb/IDBDatabase.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 15 matching lines @@
 #include "config.h"
 #include "modules/indexeddb/IDBDatabase.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "bindings/core/v8/Nullable.h"
 #include "bindings/core/v8/SerializedScriptValue.h"
 #include "bindings/modules/v8/V8BindingForModules.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/events/EventQueue.h"
+#include "core/frame/UseCounter.h"
 #include "core/inspector/ScriptCallStack.h"
 #include "modules/indexeddb/IDBAny.h"
 #include "modules/indexeddb/IDBEventDispatcher.h"
 #include "modules/indexeddb/IDBHistograms.h"
 #include "modules/indexeddb/IDBIndex.h"
 #include "modules/indexeddb/IDBKeyPath.h"
 #include "modules/indexeddb/IDBTracing.h"
 #include "modules/indexeddb/IDBVersionChangeEvent.h"
 #include "modules/indexeddb/WebIDBDatabaseCallbacksImpl.h"
 #include "public/platform/Platform.h"
@@ skipping 224 matching lines @@
     IDB_TRACE("IDBDatabase::transaction");
     Platform::current()->histogramEnumeration("WebCore.IndexedDB.FrontEndAPICalls", IDBTransactionCall, IDBMethodsMax);
 
     HashSet<String> scope;
     if (storeNames.isString()) {
         scope.add(storeNames.getAsString());
     } else if (storeNames.isStringSequence()) {
         for (const String& name : storeNames.getAsStringSequence())
             scope.add(name);
     } else if (storeNames.isDOMStringList()) {
+        UseCounter::count(executionContext(), UseCounter::IDBDatabaseTransactionStoreNamesIsDOMStringList);

[jsbell, 2015/06/05 18:12:17]

This won't tell us anything useful. Given that user code can't mint a
DOMStringList, this case is only practically exercised by:

db.transaction(db.objectStoreNames);

... where objectStoreNames yields a DOMStringList, so we'd already be counting
that usage, and if we change it to return an Array it would continue to work.

But no objection, since the data won't hurt.

[philipj_slow, 2015/06/05 18:19:22]

You're right, that sounds pretty useless, so I'll remove this. If all of the
ways of getting a DOMStringList go away, so can this.

         const Vector<String>& list = *storeNames.getAsDOMStringList();
         for (const String& name : list)
             scope.add(name);
     } else {
         ASSERT_NOT_REACHED();
     }
 
     if (scope.isEmpty()) {
         exceptionState.throwDOMException(InvalidAccessError, "The storeNames parameter was empty.");
         return nullptr;
@@ skipping 163 matching lines @@
 {
     return EventTargetNames::IDBDatabase;
 }
 
 ExecutionContext* IDBDatabase::executionContext() const
 {
     return ActiveDOMObject::executionContext();
 }
 
 } // namespace blink