Allow SessionBackend::Init() to occur just-in-time in production builds.

chrome/browser/sessions/base_session_service.h

Index: chrome/browser/sessions/base_session_service.h
diff --git a/chrome/browser/sessions/base_session_service.h b/chrome/browser/sessions/base_session_service.h
index 9c1dbb349ce0b91c0f7c3eb3ddf7fdbfc846a785..49762facf170ce46388bc35ae72142dff4f2edb0 100644
--- a/chrome/browser/sessions/base_session_service.h
+++ b/chrome/browser/sessions/base_session_service.h
@@ -149,6 +149,11 @@ class BaseSessionService : public CancelableRequestProvider,
       InternalGetCommandsRequest* request,
       CancelableRequestConsumerBase* consumer);
 
+  // Returns true if we appear to be running in production, false if
+  // we appear to be running as part of a unit test or if the FILE
+  // thread has gone away.
+  bool RunningInProduction() const;
+
   // In production, this posts the task to the FILE thread.  For
   // tests, it immediately runs the specified task on the current
   // thread.