Move MessageLoop to base namespace.

chrome/browser/sync/glue/sync_backend_host.h

Index: chrome/browser/sync/glue/sync_backend_host.h
diff --git a/chrome/browser/sync/glue/sync_backend_host.h b/chrome/browser/sync/glue/sync_backend_host.h
index 32a235400ba40ff62da9dadf789a752d68e3d650..f32709e1cfa6647cc1f4e54d3da20d38d171ef09 100644
--- a/chrome/browser/sync/glue/sync_backend_host.h
+++ b/chrome/browser/sync/glue/sync_backend_host.h
@@ -34,9 +34,12 @@
 #include "sync/protocol/encryption.pb.h"
 #include "sync/protocol/sync_protocol_error.h"
 
-class MessageLoop;
 class Profile;
 
+namespace base {
+class MessageLoop;
+}
+
 namespace syncer {
 class SyncManagerFactory;
 }
@@ -307,7 +310,7 @@ class SyncBackendHost
 
   struct DoInitializeOptions {
     DoInitializeOptions(
-        MessageLoop* sync_loop,
+        base::MessageLoop* sync_loop,
         SyncBackendRegistrar* registrar,
         const syncer::ModelSafeRoutingInfo& routing_info,
         const std::vector<syncer::ModelSafeWorker*>& workers,
@@ -328,7 +331,7 @@ class SyncBackendHost
             report_unrecoverable_error_function);
     ~DoInitializeOptions();
 
-    MessageLoop* sync_loop;
+    base::MessageLoop* sync_loop;
     SyncBackendRegistrar* registrar;
     syncer::ModelSafeRoutingInfo routing_info;
     std::vector<syncer::ModelSafeWorker*> workers;
@@ -509,7 +512,7 @@ class SyncBackendHost
 
   // A reference to the MessageLoop used to construct |this|, so we know how
   // to safely talk back to the SyncFrontend.
-  MessageLoop* const frontend_loop_;
+  base::MessageLoop* const frontend_loop_;
 
   Profile* const profile_;