Search and replace gendered terms according to style guide:

https://chromium.googlesource.com/chromium/src/+/master/styleguide/inclusive_code.md#tools

Not changin the transcipt in
resources/audio_processing/conversational_speech/README.md

BUG=webrtc:11680

Change-Id: I36af34e4a4e0ec6161093c0045b7bbe1dbe4eb45
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/177016
Reviewed-by: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31514}

examples/androidapp/src/org/appspot/apprtc/AppRTCAudioManager.java

@@ -185,8 +185,8 @@ public class AppRTCAudioManager {
     // Note that, the sensor will not be active until start() has been called.
     proximitySensor = AppRTCProximitySensor.create(context,
         // This method will be called each time a state change is detected.
-        // Example: user holds his hand over the device (closer than ~5 cm),
-        // or removes his hand from the device.
+        // Example: user holds their hand over the device (closer than ~5 cm),
+        // or removes their hand from the device.
         this ::onProximitySensorChangedState);
 
     Log.d(TAG, "defaultAudioDevice: " + defaultAudioDevice);