Don't invoke base::FeatureList access before browser startup.

base::FeatureList is initialized in the PreCreateThreads() section
of browser startup, but when running layout tests we invoke
media::RemoveProprietaryMediaTypesAndCodecsForTests() prior to even
starting the browser client. Because this method checks a
base::Feature it thus implicitly sets up features ahead of the
source of truth in PreCreateThread()

In the near term we will be deleting the media method, but that
probably won't land for a couple weeks, so in the mean time so
that we're ready for the next dev release w/ AV1, move the call
into LayoutTestContentRendererClient::RenderThreadStarted();
this isn't needed in the browser anyways.

BUG=787522,787575
TEST=no content_shell crash w/ av1 enabled.

Change-Id: I4d97d181431862d41e8abbc0ea4c4e90758f3ed5
Reviewed-on: https://chromium-review.googlesource.com/783514
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#518768}
2 files changed