feat(media): decode via RDD process and disable DRM on Android

Route audio/video decoding and encoding through the RDD process with ffvpx instead of the Android MediaCodec, which is required for playback not to crash once isolated content processes and app Zygote preloading are enabled by default. Also disable EME/DRM, whose Widevine CDM path crashes under this configuration.

Author: MrAlex94

mobile/android/app/geckoview-prefs.js

@@ -304,6 +304,27 @@ pref("media.navigator.permission.device", true);
 // this is to preserve battery and data (bug 1540573)
 pref("media.throttle-cellular-regardless-of-download-rate", true);
 
+// Waterfox: route audio/video decoding and encoding through the RDD (Remote
+// Data Decoder) process and use ffvpx instead of the Android MediaCodec. This
+// combination is required for media playback not to crash once isolated content
+// processes and app Zygote preloading are enabled by default.
+pref("media.use-remote-encoder.audio", true);
+pref("media.use-remote-encoder.video", true);
+pref("media.ffvpx-hw.enabled", true);
+pref("media.rdd-process.enabled", true);
+pref("media.rdd-ffvpx.enabled", true);
+pref("media.rdd-vorbis.enabled", true);
+pref("media.rdd-vpx.enabled", true);
+pref("media.rdd-wav.enabled", true);
+pref("media.rdd-opus.enabled", true);
+pref("media.android-media-codec.enabled", false);
+pref("media.ffmpeg.encoder.enabled", true);
+
+// Waterfox: disable EME/DRM on Android. The Widevine CDM crashes the browser
+// with the remote media configuration above, so keep EME off by default; this
+// makes DRM-protected sites fail to start the CDM rather than crash.
+pref("media.eme.enabled", false);
+
 // Increase necko buffer sizes for Android (bug 560591)
 pref("network.buffer.cache.size",  16384);