How to record audio in a StageWebView on Android ?

I have a problem regarding the recording of audio via an Android device microphone in an Adobe Air StageWebView.

Here are the relevant permission in my manifest :

<uses-permission
    android:name="android.permission.MICROPHONE"/>
<uses-feature
    android:name="android.hardware.microphone"/>
<uses-feature
    android:name="android.hardware.audio.pro"/>
<uses-permission
    android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
<uses-feature
    android:name="android.hardware.audio.low_latency"/>
<uses-permission
    android:name="android.permission.RECORD_AUDIO"/>

I'm targetting sdk 21 :

<uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="21"/>

So I don't have to ask for microphone access on runtime if I understand correctly.

Here's the error that gets thrown when I try to record audio in my webview :

Recorder unavailable: code: 0
name: "NotAllowedError"
message: "Permission denied"

Is there any solution for this ? Do I have to ask the permission on runtime ?