Remove BrowserThread::UnsafeGetBrowserThread, add UnsafeGetMessageLoopForThread.

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 92d3fe2231e9f711d0d872ecc61fdea286c7c673..7f43d43672313e93fa0de2e2a6e9a06544380680 100644
--- a/chrome/browser/sessions/base_session_service.h
+++ b/chrome/browser/sessions/base_session_service.h
@@ -8,6 +8,7 @@
 
 #include "base/basictypes.h"
 #include "base/callback.h"
+#include "base/location.h"
 #include "base/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
@@ -22,10 +23,6 @@ class SessionBackend;
 class SessionCommand;
 class TabNavigation;
 
-namespace base {
-class Thread;
-}
-
 // BaseSessionService is the super class of both tab restore service and
 // session service. It contains commonality needed by both, in particular
 // it manages a set of SessionCommands that are periodically sent to a
@@ -85,9 +82,6 @@ class BaseSessionService : public CancelableRequestProvider,
   // Returns the backend.
   SessionBackend* backend() const { return backend_; }
 
-  // Returns the thread the backend runs on. This returns NULL during testing.
-  base::Thread* backend_thread() const { return backend_thread_; }
-
   // Returns the set of commands that needed to be scheduled. The commands
   // in the vector are owned by BaseSessionService, until they are scheduled
   // on the backend at which point the backend owns the commands.
@@ -157,6 +151,12 @@ class BaseSessionService : public CancelableRequestProvider,
       InternalGetCommandsRequest* request,
       CancelableRequestConsumerBase* consumer);
 
+  // In production, this posts the task to the FILE thread.  For
+  // tests, it immediately runs the specified task on the current
+  // thread.
+  bool RunTaskOnBackendThread(const tracked_objects::Location& from_here,
+                              const base::Closure& task);
+
   // Max number of navigation entries in each direction we'll persist.
   static const int max_persist_navigation_count;
 
@@ -170,9 +170,6 @@ class BaseSessionService : public CancelableRequestProvider,
   // The backend.
   scoped_refptr<SessionBackend> backend_;
 
-  // Thread backend tasks are run on, is NULL during testing.
-  base::Thread* backend_thread_;
-
   // Used to invoke Save.
   base::WeakPtrFactory<BaseSessionService> weak_factory_;