Track webcore worker message loops in chromium.

content/common/child_thread.h

Index: content/common/child_thread.h
diff --git a/content/common/child_thread.h b/content/common/child_thread.h
index acb1e3ab4781dd23cdeea83afbca6489fa032bd2..fda01a78dce4b11ca24bf541a64d4f8b804eb942 100644
--- a/content/common/child_thread.h
+++ b/content/common/child_thread.h
@@ -18,6 +18,7 @@ class MessageLoop;
 class QuotaDispatcher;
 class ResourceDispatcher;
 class SocketStreamDispatcher;
+class WorkerTaskRunner;
 
 namespace IPC {
 class SyncChannel;
@@ -79,6 +80,8 @@ class CONTENT_EXPORT ChildThread : public IPC::Channel::Listener,
   // Returns the one child thread.
   static ChildThread* current();
 
+  WorkerTaskRunner* worker_task_runner() const;
+
  protected:
   friend class ChildProcess;
 
@@ -140,6 +143,8 @@ class CONTENT_EXPORT ChildThread : public IPC::Channel::Listener,
 
   scoped_ptr<QuotaDispatcher> quota_dispatcher_;
 
+  scoped_refptr<WorkerTaskRunner> worker_task_runner_;

[michaeln, 2011/12/05 22:02:09]

Would a leaky lazy instance be a safer/better choice for the worker task runner?
As coded in this CL, the refcounted'ness isn't used. Also do you know if worker
threads are guaranteed to be shutdown at ChildThread dtor time?

[dgrogan, 2011/12/06 00:15:15]

Not having to worry about the lifetime would be nice.  Less code, etc.
I don't think they are guaranteed to be shutdown at ChildThread dtor time.

----

After looking into this, LazyInstance seems to not add anything because
IndexedDBMessageFilter will add itself as an observer right after construction,
which is in the ChildThread ctor.  How about leaking it by removing the ref
counting and replacing scoped_refptr<WorkerTaskRunner> with WorkerTaskRunner*?

+
   DISALLOW_COPY_AND_ASSIGN(ChildThread);
 };