Add FilePath to base namespace.

chrome/browser/extensions/activity_database.h

Index: chrome/browser/extensions/activity_database.h
diff --git a/chrome/browser/extensions/activity_database.h b/chrome/browser/extensions/activity_database.h
index 89daecf661cb95e2fd2d51b4cf820eb1a742356f..1c73dc9709cb98b55dac1ec01ac57d32d9a52907 100644
--- a/chrome/browser/extensions/activity_database.h
+++ b/chrome/browser/extensions/activity_database.h
@@ -14,7 +14,9 @@
 #include "sql/connection.h"
 #include "sql/init_status.h"
 
+namespace base {
 class FilePath;
+}
 
 namespace extensions {
 
@@ -30,7 +32,7 @@ class ActivityDatabase : public base::RefCountedThreadSafe<ActivityDatabase> {
   void SetErrorDelegate(sql::ErrorDelegate* error_delegate);
 
   // Opens the DB and creates tables as necessary.
-  void Init(const FilePath& db_name);
+  void Init(const base::FilePath& db_name);
   void LogInitFailure();
 
   // Record a UrlAction in the database.