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

base/file_path.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // FilePath is a container for pathnames stored in a platform's native string
 // type, providing containers for manipulation in according with the
 // platform's conventions for pathnames.  It supports the following path
 // types:
 //
 //                   POSIX            Windows
@@ skipping 384 matching lines @@
   // directory, so "////" will become "/", not "".  A leading pair of
   // separators is never stripped, to support alternate roots.  This is used to
   // support UNC paths on Windows.
   void StripTrailingSeparatorsInternal();
 
   StringType path_;
 };
 
 }  // 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);
 
 // Macros for string literal initialization of FilePath::CharType[], and for
 // using a FilePath::CharType[] in a printf-style format string.
 #if defined(OS_POSIX)
 #define FILE_PATH_LITERAL(x) x
 #define PRFilePath "s"
 #define PRFilePathLiteral "%s"
@@ skipping 19 matching lines @@
 
 inline size_t hash_value(const base::FilePath& f) {
   return hash_value(f.value());
 }
 
 #endif  // COMPILER
 
 }  // namespace BASE_HASH_NAMESPACE
 
 #endif  // BASE_FILE_PATH_H_