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This method allows tests to force not using the BackForwardCache, this
is useful when:
  * Tests rely on a new document being loaded.
  * Tests want to specifically test the document not being in the cache.
  * Any other reason BFCache doesn't make sense for a particular test.

Change-Id: I07fbc0a31023a78109268c100e5f454dbfbed13f
Bug: 973855,965925
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1657836Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Commit-Queue: Lowell Manners <lowell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683552}