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This implements TabSpecificContentSettings for weblayer, and syncs
content settings to the renderer similar to what is done for chrome. A
couple client hints tests are added which depend on the content settings
syncing behavior to make sure it's working.

Bug: 1070825, 1065537
Change-Id: I72946341ae8e0932663ffb1ef72954b0a7897b1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2153314Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760177}