Provides the ability to block the device / display from sleeping.

On Android, the implementation is inherently coupled to the NativeView associated with the context of the requestor due to system APIs. To handle this coupling, the Wake Lock usage model on Android is as follows:

(1) The embedder passes in a callback at Device Service construction that enables the Wake Lock implementation to map (embedder-specific) context IDs to NativeViews. (2) For a given embedder-specific context, a trusted client connects to the WakeLockProvider interface and gets a WakeLockContext instance that is associated with that context. (3) That trusted client then forwards requests to bind wake locks from untrusted clients that are made within that context, with the Wake Lock implementation using the callback from (1) as necessary to obtain the NativeView associated with that context.

On other platforms, the usage model is similar but the callback is not necessary/employed.

If the client does not have any context available (e.g., is not within the context of a WebContents), it can get a WakeLock that doesn't associate to any context (by GetWakeLockWithoutContext() in WakeLockProvider). However, note that the resulting Wake Lock will not have any effect on Android.