Add explicit base to FilePath.

content/test/webrtc_audio_device_test.cc

Index: content/test/webrtc_audio_device_test.cc
diff --git a/content/test/webrtc_audio_device_test.cc b/content/test/webrtc_audio_device_test.cc
index 571c4a6621963a78bc6cfb1748ce8dbf1ee64e38..13f79c8d6f9d92597bab3698f810487e9564e04a 100644
--- a/content/test/webrtc_audio_device_test.cc
+++ b/content/test/webrtc_audio_device_test.cc
@@ -336,8 +336,8 @@ void WebRTCAudioDeviceTest::WaitForMessageLoopCompletion(
 }
 
 std::string WebRTCAudioDeviceTest::GetTestDataPath(
-    const FilePath::StringType& file_name) {
-  FilePath path;
+    const base::FilePath::StringType& file_name) {
+  base::FilePath path;
   EXPECT_TRUE(PathService::Get(DIR_TEST_DATA, &path));
   path = path.Append(file_name);
   EXPECT_TRUE(file_util::PathExists(path));