mus: Introduce AttachSurface to allow creating Surface prior to OnEmbed
RenderWidget::CreateOutputSurface is called prior to the availability of a
RenderWidgetMusConnection, and prior to notification of embedding in
Mus (RenderWidgetMusConnection::OnEmbed). This CL provides a
mechanism to create a WindowSurface prior to the availability of a
Window. When creating a WindowSurface, a sibling object,
WindowSurfaceBinding is also created that can be passed into
Window::AttachSurface once a mus::Window is available.
BUG=551250
Review URL: https://codereview.chromium.org/1484533002
Cr-Commit-Position: refs/heads/master@{#362273}
11 files changed
