Move MessageLoop to base namespace.

chrome/browser/printing/print_job_worker_owner.h

Index: chrome/browser/printing/print_job_worker_owner.h
diff --git a/chrome/browser/printing/print_job_worker_owner.h b/chrome/browser/printing/print_job_worker_owner.h
index 7224fd33bf5d49e2c5cc91ce7cffda358059565a..8f9f58509f1fd3e5b92461fa1ddfc891f18eec15 100644
--- a/chrome/browser/printing/print_job_worker_owner.h
+++ b/chrome/browser/printing/print_job_worker_owner.h
@@ -8,7 +8,10 @@
 #include "base/memory/ref_counted.h"
 #include "printing/printing_context.h"
 
+namespace base {
 class MessageLoop;
+}
+
 
 namespace printing {
 
@@ -28,7 +31,7 @@ class PrintJobWorkerOwner
   virtual PrintJobWorker* DetachWorker(PrintJobWorkerOwner* new_owner) = 0;
 
   // Retrieves the message loop that is expected to process GetSettingsDone.
-  virtual MessageLoop* message_loop() = 0;
+  virtual base::MessageLoop* message_loop() = 0;
 
   // Access the current settings.
   virtual const PrintSettings& settings() const = 0;