Move MessageLoop to base namespace.

chrome/browser/autocomplete/history_url_provider.h

Index: chrome/browser/autocomplete/history_url_provider.h
diff --git a/chrome/browser/autocomplete/history_url_provider.h b/chrome/browser/autocomplete/history_url_provider.h
index 7d40a084f68bceefb86c9ed8a4a58c70da45693e..1a3a3ea5bb2631fb705046bf42bade593e59ab8f 100644
--- a/chrome/browser/autocomplete/history_url_provider.h
+++ b/chrome/browser/autocomplete/history_url_provider.h
@@ -17,9 +17,12 @@
 #include "chrome/browser/search_engines/search_terms_data.h"
 #include "chrome/browser/search_engines/template_url.h"
 
-class MessageLoop;
 class Profile;
 
+namespace base {
+class MessageLoop;
+}
+
 namespace history {
 class HistoryBackend;
 class URLDatabase;
@@ -93,7 +96,7 @@ struct HistoryURLProviderParams {
                            const SearchTermsData& search_terms_data);
   ~HistoryURLProviderParams();
 
-  MessageLoop* message_loop;
+  base::MessageLoop* message_loop;
 
   // A copy of the autocomplete input. We need the copy since this object will
   // live beyond the original query while it runs on the history thread.