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This CL renames ChromeBrowserPluginDelegate to GuestViewContainer and moves it to extensions

This CL moves guest_view_constants to extensions/common/*

This CL also attaches a GuestViewContainer to all GuestViews.

BUG=330264, 352290

Review URL: https://codereview.chromium.org/577453002

Cr-Commit-Position: refs/heads/master@{#295034}