Disable "using base::FilePath" on Linux since it now compiles.

base/file_path.h

Index: base/file_path.h
diff --git a/base/file_path.h b/base/file_path.h
index e5c4b846f1c37fd61c95c9e7a202aa734df1e75e..c01da94026801a57a6933081e06b3c389ec3240d 100644
--- a/base/file_path.h
+++ b/base/file_path.h
@@ -402,8 +402,15 @@ class BASE_EXPORT FilePath {
 
 }  // namespace base
 
-// TODO(brettw) remove this once callers properly use the base namespace.
+// Temporarily have non-Linux platforms use a "using" so we can convert those
+// over one-at-a-time.
+//
+// http://crosbug.com/39008 MTPD has a circular dependency on base and uses the
+// old non-namespaced FilePath.
+#if defined(MTPD_DEVICE_MANAGER_H_) || defined(OS_CHROMEOS) || \
+    !defined(OS_LINUX)
 using base::FilePath;
+#endif
 
 // This is required by googletest to print a readable output on test failures.
 BASE_EXPORT extern void PrintTo(const base::FilePath& path, std::ostream* out);