Upstream HostedAppButtonContainer container logic into BrowserNonClientFrameView

Subclasses of BrowserNonClientFrameView that contain a HostedAppButtonContainer
child view have duplicate logic outside of creation, colors and layout.

This CL dedupes the logic involved in having a HostedAppButtonContainer
in preparation for adding one to BrowserNonClientFrameViewMac.

Bug: 895690
Change-Id: If2e5d58af58cd72ea9d0902d3a15f3375a9e1585
Reviewed-on: https://chromium-review.googlesource.com/c/1288092
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601427}
10 files changed