Adding comment regarding the disabling the flaky test VolumeTest.ManualRequiresMicrophoneCanSetMicr…

webrtc/voice_engine/test/auto_test/standard/volume_test.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 155 matching lines @@
   EXPECT_TRUE(could_get_mic_volume);
 #endif
   if (could_get_mic_volume) {
     EXPECT_LE(volume, 255u);
   } else {
     TEST_LOG("Failed to get the microphone volume.");
     EXPECT_EQ(1000u, volume);
   }
 }
 
+// The test below is disabled due to issue webrtc:6206.
 TEST_F(VolumeTest, DISABLED_ManualRequiresMicrophoneCanSetMicrophoneVolumeWithAgcOff) {
   SwitchToManualMicrophone();
   EXPECT_EQ(0, voe_apm_->SetAgcStatus(false));
 
   unsigned int original_volume = 0;
   bool could_get_mic_volume =
       (voe_volume_control_->GetMicVolume(original_volume) == 0);
 #if !defined(WEBRTC_LINUX)
   EXPECT_TRUE(could_get_mic_volume);
 #endif
@@ skipping 106 matching lines @@
   Sleep(1000);
 
   // To finish, verify that the getter works.
   float left = 0.0f;
   float right = 0.0f;
 
   EXPECT_EQ(0, voe_volume_control_->GetOutputVolumePan(channel_, left, right));
   EXPECT_FLOAT_EQ(0.1f, left);
   EXPECT_FLOAT_EQ(0.8f, right);
 }