Oilpan: DatabaseThread::m_thread should not get destructed during sweeping

Source/modules/webdatabase/DatabaseContext.cpp

Index: Source/modules/webdatabase/DatabaseContext.cpp
diff --git a/Source/modules/webdatabase/DatabaseContext.cpp b/Source/modules/webdatabase/DatabaseContext.cpp
index 456087abd8cf1966d3cf3df6aa1164b1affae824..ba458daf6b9259a0ec5ae11d9059b469ce3144cf 100644
--- a/Source/modules/webdatabase/DatabaseContext.cpp
+++ b/Source/modules/webdatabase/DatabaseContext.cpp
@@ -182,6 +182,7 @@ void DatabaseContext::stopDatabases()
         m_databaseThread->requestTermination(&sync);
         m_hasRequestedTermination = true;
         sync.waitForTaskCompletion();
+        m_databaseThread->dispose();

[wibling-chromium, 2014/09/23 08:40:59]

It would be nice with a comment explaining why it is safe to dispose of the
webthread at this point. Ie. something like the sync.waitForTaskCompletion will
not return until the cleanupDatabaseThreadCompleted method has been called at
which point the webthread should no longer be reused.

That said I am not that familiar with the code to say there cannot be a new
scheduleTask call before the context is destructed?

[zerny-chromium, 2014/09/23 08:46:29]

Alternatively we could encapsulate this in the database thread abstraction, ala:

DatabaseThread::terminate(bool* terminating)
{
    TaskSynchronizer sync;
    requestTermination(&sync);
    *terminating = true;
    sync.waitForTaskCompletion();
    // Oilpan: comment about waiting before clearing goes here.
    m_thread.clear();
}

That would avoid a public dispose and some out-of-context reasoning.

     }
 }