Psuedo revert "s/scheduleLayerUpdate/setNeedsCompositingUpdate in setWebLayer."

This method has been renamed already, so it's not a strict revert, but
it restores the original behavior.

BUG=none
TEST=browser_tests --gtest_filter=WebViewTest*Auto*
TBR=ojan@chromium.org

Review URL: https://codereview.chromium.org/316373005

git-svn-id: svn://svn.chromium.org/blink/trunk@175620 bbb929c8-8fbe-4397-9dbb-9b2b20218538