Add FilePath to base namespace.

remoting/host/audio_capturer_linux.h

Index: remoting/host/audio_capturer_linux.h
diff --git a/remoting/host/audio_capturer_linux.h b/remoting/host/audio_capturer_linux.h
index b52f1ff9e57ec1d0a2ee8a2578bf43cc6c7f7adb..466ccf6cd4d82648567c66edc9f95a08e8a5a257 100644
--- a/remoting/host/audio_capturer_linux.h
+++ b/remoting/host/audio_capturer_linux.h
@@ -10,7 +10,9 @@
 #include "remoting/host/audio_silence_detector.h"
 #include "remoting/host/linux/audio_pipe_reader.h"
 
+namespace base {
 class FilePath;
+}
 
 namespace remoting {
 
@@ -24,7 +26,7 @@ class AudioCapturerLinux : public AudioCapturer,
   // to read from the pipe.
   static void InitializePipeReader(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-      const FilePath& pipe_name);
+      const base::FilePath& pipe_name);
 
   explicit AudioCapturerLinux(
       scoped_refptr<AudioPipeReader> pipe_reader);