class WireWeakAsyncBufferClientImpl

A hanging get for receiving the status of a View. This provides information to the parent,

such as whether or not the child has successfully presented content through this View.

This hanging get will only fire when the ChildViewStatus is different than the previously

returned ChildViewStatus. This can happen immediately, and even if the creator of the

Viewport hasn't yet called Present() after calling CreateViewport(). This allows the parent

to know that the child has content ready to display before the parent modifies their own

local scene graph to incorporate the child content.

It is invalid to call `GetStatus` while a previous call is still pending. Doing so will

cause both this channel and the Flatland channel that handed out ChildViewWatcher to be

closed.

Caller provides the backing storage for FIDL message.

Hanging get to receive the ViewRef of the child View. This will only fire when the View ref

is different from the previously-returned View ref. Note: currently the View ref will not

change after it is first received, but this will change if/when the API changes to allow

relinking of views.

The ViewRef is not returned until the View is included in the View tree, in other words when

there is a chain of ancestor transforms all the way back up to the root of the scene graph,

i.e. the display.

It is invalid to call `GetViewRef` while a previous call is still pending. Doing so will

cause both this channel and the Flatland channel that handed out ChildViewWatcher to be

closed.

A `GetViewRef` call will hang if the View was created using `CreateView`, but returns the

View if the View was created using CreateView2. This is because `CreateView` does not mint

a ViewRef for that View.

Caller provides the backing storage for FIDL message.