Kill worker process by way of a sync IPC message before it cleans up.

content/common/worker_messages.h

Index: content/common/worker_messages.h
diff --git a/content/common/worker_messages.h b/content/common/worker_messages.h
index 6f20461ec3ed181313aa853c39ed0324be2425a2..75eff19d3ffbea4d11ed067d85f675b513ab61cd 100644
--- a/content/common/worker_messages.h
+++ b/content/common/worker_messages.h
@@ -142,6 +142,10 @@ IPC_SYNC_MESSAGE_CONTROL3_1(WorkerProcessHostMsg_AllowIndexedDB,
                             string16 /* database name */,
                             bool /* result */)
 
+// Sent by the worker process to request being killed.
+IPC_SYNC_MESSAGE_CONTROL0_0(WorkerProcessHostMsg_ForceKillWorker);
+
+
 //-----------------------------------------------------------------------------
 // Worker messages
 // These are messages sent from the renderer process to the worker process.