Fix Chromium clang plugin warnings

NOTRY=true
BUG=webrtc:163

Review-Url: https://codereview.webrtc.org/2291503002
Cr-Commit-Position: refs/heads/master@{#13959}
diff --git a/webrtc/modules/audio_coding/test/Channel.h b/webrtc/modules/audio_coding/test/Channel.h
index 5910fad..c45864a 100644
--- a/webrtc/modules/audio_coding/test/Channel.h
+++ b/webrtc/modules/audio_coding/test/Channel.h
@@ -47,7 +47,7 @@
  public:
 
   Channel(int16_t chID = -1);
-  ~Channel();
+  ~Channel() override;
 
   int32_t SendData(FrameType frameType,
                    uint8_t payloadType,
diff --git a/webrtc/modules/audio_coding/test/PCMFile.cc b/webrtc/modules/audio_coding/test/PCMFile.cc
index 9289d73..b4acf35 100644
--- a/webrtc/modules/audio_coding/test/PCMFile.cc
+++ b/webrtc/modules/audio_coding/test/PCMFile.cc
@@ -46,6 +46,12 @@
   timestamp_ = timestamp;
 }
 
+PCMFile::~PCMFile() {
+  if (pcm_file_) {
+    fclose(pcm_file_);
+  }
+}
+
 int16_t PCMFile::ChooseFile(std::string* file_name, int16_t max_len,
                             uint16_t* frequency_hz) {
   char tmp_name[MAX_FILE_NAME_LENGTH_BYTE];
diff --git a/webrtc/modules/audio_coding/test/PCMFile.h b/webrtc/modules/audio_coding/test/PCMFile.h
index 840933a..b5ced0b 100644
--- a/webrtc/modules/audio_coding/test/PCMFile.h
+++ b/webrtc/modules/audio_coding/test/PCMFile.h
@@ -26,11 +26,7 @@
  public:
   PCMFile();
   PCMFile(uint32_t timestamp);
-  ~PCMFile() {
-    if (pcm_file_ != NULL) {
-      fclose(pcm_file_);
-    }
-  }
+  ~PCMFile();
 
   void Open(const std::string& filename, uint16_t frequency, const char* mode,
             bool auto_rewind = false);
diff --git a/webrtc/modules/audio_coding/test/utility.h b/webrtc/modules/audio_coding/test/utility.h
index 23869be..dbd398e 100644
--- a/webrtc/modules/audio_coding/test/utility.h
+++ b/webrtc/modules/audio_coding/test/utility.h
@@ -118,10 +118,8 @@
 class VADCallback : public ACMVADCallback {
  public:
   VADCallback();
-  ~VADCallback() {
-  }
 
-  int32_t InFrameType(FrameType frame_type);
+  int32_t InFrameType(FrameType frame_type) override;
 
   void PrintFrameTypes();
   void Reset();