Add FilePath to base namespace.

chrome/browser/extensions/external_provider_interface.h

Index: chrome/browser/extensions/external_provider_interface.h
diff --git a/chrome/browser/extensions/external_provider_interface.h b/chrome/browser/extensions/external_provider_interface.h
index 1d1f098e68f07e6899ad66ed524c0147b399aeef..20173864d4c8403a88f20c3191774cb46e855c56 100644
--- a/chrome/browser/extensions/external_provider_interface.h
+++ b/chrome/browser/extensions/external_provider_interface.h
@@ -10,10 +10,13 @@
 #include "base/memory/linked_ptr.h"
 #include "chrome/common/extensions/manifest.h"
 
-class FilePath;
 class GURL;
 class Version;
 
+namespace base {
+class FilePath;
+}
+
 namespace extensions {
 
 // This class is an abstract class for implementing external extensions
@@ -33,7 +36,7 @@ class ExternalProviderInterface {
     virtual bool OnExternalExtensionFileFound(
         const std::string& id,
         const Version* version,
-        const FilePath& path,
+        const base::FilePath& path,
         Manifest::Location location,
         int creation_flags,
         bool mark_acknowledged) = 0;