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This involves a bit of restructuring. This change:
1) Introduces ShellSurface::Set{Parent,Container}Internal, which ensure
   that the minimize/maximize/resize state is correctly updated when
   these properties change;
2) Makes ShellSurface::parent_ private instead of protected so subclasses
   can't accidentally change it without using the new internal setter;
3) Has these internal setters and the ShellSurface constructor set the
   state of CanMaximize/CanMinimize/CanResize

Bug: 1075649
Change-Id: I019ce03248eef3aea6ac16c509f2e5d3312fb940
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2472615Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817269}