Bug xxxxxx - Add a helper to APZCCallbackHelper to obtain the presShellId and viewId. r=
Bug xxxxxx - Refactor some code to extract a TabChild::GetDocument method. r=
Bug xxxxxx - Pass the presShellId and viewId from TabChild to RenderFrameParent when updating zoom constraints. r=
Bug xxxxxx - Pass the presShellId and viewId from TabChild to RenderFrameParent when requesting a zoom. r=