Enable cpplint and fix cpplint errors in webrtc/*audio

webrtc/common_audio/vad/vad_gmm_unittest.cc

Index: webrtc/common_audio/vad/vad_gmm_unittest.cc
diff --git a/webrtc/common_audio/vad/vad_gmm_unittest.cc b/webrtc/common_audio/vad/vad_gmm_unittest.cc
index 9de93f67f02121ea21b59322aa7fea1eb10b0d15..7d95111846837757ac560fee2ae64e352a24a407 100644
--- a/webrtc/common_audio/vad/vad_gmm_unittest.cc
+++ b/webrtc/common_audio/vad/vad_gmm_unittest.cc
@@ -16,7 +16,8 @@ extern "C" {
 #include "webrtc/common_audio/vad/vad_gmm.h"
 }
 
-namespace {
+namespace webrtc {
+namespace test {
 
 TEST_F(VadTest, vad_gmm) {
   int16_t delta = 0;
@@ -40,4 +41,5 @@ TEST_F(VadTest, vad_gmm) {
   EXPECT_EQ(0, WebRtcVad_GaussianProbability(105, 0, 128, &delta));
   EXPECT_EQ(13440, delta);
 }
-}  // namespace
+}  // namespace test
+}  // namespace webrtc