Unflag Audio Output Devices API in Blink.

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in

 // http://dev.chromium.org/blink/runtime-enabled-features
 //
 // This list is used to generate RuntimeEnabledFeatures.h/cpp which contains
 // a class that stores static enablers for all experimental features.
 //
 // Each feature can be assigned a "status":
 // status=stable -> Enable this in all Blink configurations.  We are committed to these APIs indefinitely.
 // status=experimental -> In-progress features, Web Developers might play with, but are not on by default in stable.
 // status=test -> Enabled in ContentShell for testing, otherwise off.
 // Features without a status are not enabled anywhere by default.
 //
 // "implied_by" or "depends_on" specifies relationship to other features:
 // implied_by=feature1[,feature2,...] -> The feature is automatically enabled if any implied_by features is enabled;
 // depends_on=feature1[,feature2,...] -> The feature is enabled only if all depends_on features are enabled.
 // Only one of "implied_by" and "depends_on" can be specified.
 //
 // "stable" features listed here should be rare, as anything which we've shipped stable
 // can have its runtime flag removed soon after.
 //
 // condition=ENABLE_NAME is used for wrapping features in compile-time
 // #if ENABLE(FEATURE) guards.  These are deprecated and should all be removed.
 //
 // api_name=API_NAME is used to enable the feature through the experimental framework, so that the feature can be
 // enabled at runtime on a per-page basis through a signed API key for the corresponding API name.
 
 AdditiveAnimations status=experimental, depends_on=StackedCSSPropertyAnimations
 AppBanner status=stable
 AlwaysUseComplexText status=stable
 ApplicationCache status=stable
-AudioOutputDevices status=experimental
+AudioOutputDevices status=stable
 AudioVideoTracks depends_on=Media, status=experimental
 AuthorShadowDOMForAnyElement
 BackgroundSync status=stable
 BackgroundSyncV2 status=experimental
 CacheStorageMatchAll status=stable
 ClientHints status=stable
 ColumnFill status=experimental
 CompositedSelectionUpdate
 CompositorWorker status=experimental
 // Unified Chrome Compositor and Blink Animations engine (Project Heaviside). crbug.com/394772
@@ skipping 159 matching lines @@
 WebGLImageChromium
 WebUSB status=experimental
 WebVR depends_on=GeometryInterfaces, status=test
 WebVTTRegions depends_on=Media, status=experimental
 V8IdleTasks
 XSLT status=stable
 smil status=stable
 ScrollCustomization
 ScrollRestoration status=stable
 WakeLock status=experimental