Oilpan: Prepare to move SQLTransactionBackendSync and SQLTransactionSync to Oilpan heap.

Source/modules/webdatabase/DatabaseSync.h

Index: Source/modules/webdatabase/DatabaseSync.h
diff --git a/Source/modules/webdatabase/DatabaseSync.h b/Source/modules/webdatabase/DatabaseSync.h
index 07052c87ae1daa2a5dbb7253d9e1296b343fe0f2..f1317c36cb352ab0dbb02cb1f44a7fc390472f99 100644
--- a/Source/modules/webdatabase/DatabaseSync.h
+++ b/Source/modules/webdatabase/DatabaseSync.h
@@ -62,6 +62,7 @@ public:
     void readTransaction(PassOwnPtr<SQLTransactionSyncCallback>, ExceptionState&);
 
     virtual void closeImmediately() OVERRIDE;
+    void observeTransaction(SQLTransactionSync&);
 
     const String& lastErrorMessage() const { return m_lastErrorMessage; }
     void setLastErrorMessage(const String& message) { m_lastErrorMessage = message; }
@@ -76,7 +77,20 @@ private:
     static PassRefPtrWillBeRawPtr<DatabaseSync> create(ExecutionContext*, PassRefPtrWillBeRawPtr<DatabaseBackendBase>);
 
     void runTransaction(PassOwnPtr<SQLTransactionSyncCallback>, bool readOnly, ExceptionState&);
-    void rollbackTransaction(PassRefPtr<SQLTransactionSync>);
+    void rollbackTransaction(SQLTransactionSync&);
+#if ENABLE(OILPAN)
+    class TransactionObserver {
+    public:
+        explicit TransactionObserver(SQLTransactionSync& transaction) : m_transaction(transaction) { }
+        ~TransactionObserver();
+
+    private:
+        SQLTransactionSync& m_transaction;
+    };
+
+    GC_PLUGIN_IGNORE("http://crbug.com/353083")
+    PersistentHeapHashMap<WeakMember<SQLTransactionSync>, OwnPtr<TransactionObserver> > m_observers;

[haraken, 2014/03/18 09:59:09]

I'd like to have a comment about why this needs to be persistent.

[zerny-chromium, 2014/03/18 10:09:09]

I think the bug report provides sufficient documentation here.

[haraken, 2014/03/18 11:31:33]

I want to have a comment about the threading issue of this specific case. I
couldn't get it until mads explained it in the issue tracker :)

[tkent, 2014/03/19 04:58:39]

I'll add a comment.

+#endif
 
     String m_lastErrorMessage;